Add content to PHP roadmap (#7895)

* Section 1

* Section 2

* Section 3

* Section 4

* Section 5

src/data/roadmaps/php/content/_get@GFYGFVfxkOoPI5mI4zSt1.md

@@ -2,19 +2,19 @@
 
 $_GET is a pre-defined array in PHP, that's used to collect form-data sent through HTTP GET method. It's useful whenever you need to process or interact with data that has been passed in via a URL's query string. For an example if you have a form with a GET method, you can get the values of the form elements through this global $_GET array. Here’s an example: 
 
-```php
+```html
 <form method="get" action="test.php">
   Name: <input type="text" name="fname">
   <input type="submit">
 </form>
 ```
 
-Using $_GET, you can fetch the 'fname' value from the URL:
+Using $_GET in `test.php`, you can fetch the 'fname' value from the URL:
 
 ```php
 echo "Name is: " . $_GET['fname'];
 ```
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation](https://www.php.net/manual/en/reserved.variables.get.php)
+- [@official@$_GET](https://www.php.net/manual/en/reserved.variables.get.php)

src/data/roadmaps/php/content/_post@qNG-a4iIO-puZsMwAMzYC.md

@@ -2,16 +2,16 @@
 
 `$_POST` is a superglobal variable in PHP that's used to collect form data submitted via HTTP POST method. Your PHP script can access this data through `$_POST`. Let's say you have a simple HTML form on your webpage. When the user submits this form, the entered data can be fetched using `$_POST`. Here's a brief example:
 
-```
+```php
 <?php
 if ($_SERVER["REQUEST_METHOD"] == "POST") {
     $name = $_POST["name"];
 }
 ?>
 ```
 
-In this code, $_POST["name"] fetches the value entered in the 'name' field of the form. Always be cautious when using `$_POST` as it may contain user input which is a common source of vulnerabilities. Always validate and sanitize data from `$_POST` before using it.
+In this code, `$_POST["name"]` fetches the value entered in the 'name' field of the form. Always be cautious when using `$_POST` as it may contain user input which is a common source of vulnerabilities. Always validate and sanitize data from `$_POST` before using it.
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation](https://www.php.net/manual/en/reserved.variables.post.php)
+- [@official@$_POST](https://www.php.net/manual/en/reserved.variables.post.php)

src/data/roadmaps/php/content/_request@A6rfW4uJhyfAX2b18_EEC.md

@@ -2,12 +2,12 @@
 
 $_REQUEST is a PHP superglobal variable that contains the contents of both $_GET, $_POST, and $_COOKIE. It is used to collect data sent via both the GET and POST methods, as well as cookies. $_REQUEST is useful if you do not care about the method used to send data, but its usage is generally discouraged as it could lead to security vulnerabilities. Here's a simple example:
 
-```
+```php
 $name = $_REQUEST['name'];
 ```
 
 This statement will store the value of the 'name' field sent through either a GET or POST method. Always remember to sanitize user input to avoid security problems.
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation](https://www.php.net/manual/en/reserved.variables.request.php)
+- [@official@$_REQUEST](https://www.php.net/manual/en/reserved.variables.request.php)

src/data/roadmaps/php/content/_server@7Ja2at_N9tRTlvSGahrqn.md

@@ -10,4 +10,4 @@ echo 'Your IP is: ' . $_SERVER['REMOTE_ADDR'];
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation](https://www.php.net/reserved.variables.server)
+- [@official@$_SERVER](https://www.php.net/reserved.variables.server)

src/data/roadmaps/php/content/abstract-classes@ub79EkMiOmPBwXLRuYFL8.md

@@ -4,4 +4,4 @@ Abstract classes in PHP are those which cannot be instantiated on their own. The
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation](https://www.php.net/manual/en/language.oop5.abstract.php)
+- [@official@Abstract Classes](https://www.php.net/manual/en/language.oop5.abstract.php)

src/data/roadmaps/php/content/access-specifiers@RD2RaBmA2XWkEa13PTCTX.md

@@ -4,4 +4,4 @@ Access specifiers, also known as access modifiers, in PHP are keywords used in t
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation](https://www.php.net/manual/en/language.oop5.visibility.php)
+- [@official@Access Specifiers & Visibility](https://www.php.net/manual/en/language.oop5.visibility.php)

src/data/roadmaps/php/content/anonymous-functions@Nr5m6wQLp7VyG3AucrSc8.md

@@ -16,4 +16,4 @@ In this example, we're creating an anonymous function and assigning it to the va
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation - Anonymous Functions](https://www.php.net/manual/en/functions.anonymous.php)
+- [@official@Anonymous Functions](https://www.php.net/manual/en/functions.anonymous.php)

src/data/roadmaps/php/content/apache@KMQqePqAjQ-ReDwHqeofx.md

@@ -4,5 +4,5 @@ Apache is a popular web server that can efficiently host PHP applications. Apach
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentations - Apache](https://www.php.net/manual/en/install.unix.apache2.php)
-- [@official@Apache Website](https://httpd.apache.org/)
+- [@official@Apache PHP Documentation](https://www.php.net/manual/en/install.unix.apache2.php)
+- [@official@Apache](https://httpd.apache.org/)

src/data/roadmaps/php/content/arrays@IhKjvT6CjRz4dsSU7SNQo.md

@@ -4,4 +4,4 @@ Arrays in PHP are fundamental data structures that store multiple elements in a
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation - Arrays](https://www.php.net/manual/en/language.types.array.php)
+- [@official@Arrays](https://www.php.net/manual/en/language.types.array.php)

src/data/roadmaps/php/content/arrow-functions@mP1BIkqbWVVTU-zZv1ZL6.md

@@ -4,4 +4,4 @@ Arrow functions provide a more concise syntax to create anonymous functions. The
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation - Arrow Functions](https://www.php.net/manual/en/functions.arrow.php)
+- [@official@Arrow Functions](https://www.php.net/manual/en/functions.arrow.php)

src/data/roadmaps/php/content/auth-mechanisms@HJJzKYXdK4BWITLP4APLZ.md

@@ -4,4 +4,4 @@ When you are developing PHP application, security should always be a top priorit
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation - Auth Mechanisms](https://www.php.net/manual/en/features.http-auth.php)
+- [@official@Auth Mechanisms](https://www.php.net/manual/en/features.http-auth.php)

src/data/roadmaps/php/content/autoloading@qFiTsf6Es-gwqe6J6bdL1.md

@@ -14,4 +14,4 @@ In this example, PHP will automatically load the MyClass.php file when the MyCla
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation - Autloading](https://www.php.net/manual/en/language.oop5.autoload.php)
+- [@official@Autoloading](https://www.php.net/manual/en/language.oop5.autoload.php)

src/data/roadmaps/php/content/basic-php-syntax@hzBUHSuFwLYNooF_vEmrs.md

@@ -4,4 +4,4 @@ PHP syntax is generally considered similar to C-style syntax, where code blocks
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation - Basic Syntax](https://www.php.net/manual/en/langref.php)
+- [@official@Basic Syntax](https://www.php.net/manual/en/langref.php)

src/data/roadmaps/php/content/caching-strategies@Av-BMa57RvrLlAXLffOH0.md

@@ -4,4 +4,4 @@ Caching Strategies are integral to Performance Optimization in PHP. Caching mini
 
 Visit the following resources to learn more:
 
-- [@official@Official Documentation - Opcache](https://www.php.net/manual/en/book.opcache.php)
+- [@official@Opcache](https://www.php.net/manual/en/book.opcache.php)

src/data/roadmaps/php/content/callback-functions@x7hA2KAzJIjc-prgCEw6V.md

@@ -1,7 +1,7 @@
 # Callback Functions
 
-A callback function will use that function on whatever data is returned by a particular method.
+A callback function in PHP is a function that is passed as an argument to another function. The receiving function can then invoke this function as needed. Callback functions are often used to define flexible or reusable code because they allow you to customize the behavior of a function without changing its structure.
 
 Visit the following resources to learn more:
 
-- [@official@Official Documentation - Callback functions](https://www.php.net/manual/en/language.types.callable.php)
+- [@official@Callback Functions](https://www.php.net/manual/en/language.types.callable.php)

src/data/roadmaps/php/content/casting-data-types@pzReF4C0mcCWAnpfIJbwl.md

@@ -2,6 +2,15 @@
 
 PHP, as a loose typing language, allows us to change the type of a variable or to transform an instance of one data type into another. This operation is known as Casting. When to use casting, however, depends on the situation - it is recommendable when you want explicit control over the data type for an operation. The syntax involves putting the intended type in parentheses before the variable. For example, if you wanted to convert a string to an integer, you'd use: `$myVar = "123"; $intVar = (int) $myVar;`. Here, `$intVar` would be an integer representation of `$myVar`. Remember, the original variable type remains unchanged. 
 
+Here's an example of type casting in PHP:
+
+```php
+<?php
+$foo = 10;   // $foo is an integer
+$bar = (bool) $foo;   // $bar is a boolean
+?>
+```
+
 Visit the following resources to learn more:
 
-- [@official@Official Documentation - Type Casting](https://www.php.net/manual/en/language.types.type-juggling.php)
+- [@official@Type Casting](https://www.php.net/manual/en/language.types.type-juggling.php)

src/data/roadmaps/php/content/classes-and-objects@PIuplWreo7PFG3Mdn2t6W.md

@@ -4,4 +4,4 @@ PHP supports object-oriented programming, offering a multi-paradigm way of codin
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation - Classes](https://www.php.net/manual/en/language.oop5.php)
+- [@official@Classes](https://www.php.net/manual/en/language.oop5.php)

src/data/roadmaps/php/content/composer@yVFDu2aTiEZ4PWMdKdW2P.md

@@ -10,4 +10,5 @@ This command adds the `vendor/package` dependency to your project. The same goes
 
 Visit the following resources to learn more:
 
-- [@official@Composer Official Website](https://getcomposer.org/doc/)
+- [@official@Composer](https://getcomposer.org/)
+- [@official@Composer Documentation](https://getcomposer.org/doc/)

src/data/roadmaps/php/content/conditionals@38YksjvhXCbgnHqkl57Cz.md

@@ -4,4 +4,4 @@ Conditionals in PHP, much like in other programming languages, allow for branchi
 
 Visit the following resources to learn more:
 
-- [@official@Official Documentation - Control Structures](https://www.php.net/manual/en/language.control-structures.php)
+- [@official@Control Structures](https://www.php.net/manual/en/language.control-structures.php)

src/data/roadmaps/php/content/configuration-files@DTaAZaU1CwzW7esoDhj85.md

@@ -4,4 +4,4 @@ Configuration files are critical for PHP applications because they help manage d
 
 Visit the following resources to learn more:
 
-- [@official@Official Documentation - PHP Config](https://www.php.net/manual/en/ini.list.php)
+- [@official@PHP Config](https://www.php.net/manual/en/ini.list.php)

src/data/roadmaps/php/content/configuration-tuning@VpwwF8j5ZtXVSbzNfE7Sx.md

@@ -12,4 +12,4 @@ ini_set('max_execution_time', '300');
 
 Visit the following resources to learn more:
 
-- [@official@Official Documentation - PHP.ini](https://www.php.net/manual/en/ini.core.php)
+- [@official@Configuration Tuning](https://www.php.net/manual/en/ini.core.php)

src/data/roadmaps/php/content/connection-pooling@txUyPR_tdC8iTJV3RtvBz.md

@@ -2,4 +2,7 @@
 
 Connection pooling is a technique used in PHP to manage and maintain multiple open connections with a database. It reduces the time overhead of constantly opening and closing connections, and ensures efficient utilisation of resources. Connection pooling limits the number of connections opened with the database and instead reuses a pool of existing active connections, thereby significantly enhancing the performance of PHP applications. When a PHP script needs to communicate with the database, it borrows a connection from this pool, performs the operations, and then returns it back to the pool. Although PHP doesn't have native support for connection pooling, it can be achieved through third-party tools like 'pgBouncer' when using PostgreSQL or 'mysqlnd_ms' plugin with MySQL. Note, it's recommended to use connection pooling when you've a high-traffic PHP application. 
 
-For more information, visit PHP Database Extensions [here](https://www.php.net/manual/en/refs.database.php).
+Visit the following resources to learn more:
+
+- [@official@Connection Pooling](https://www.php.net/manual/en/oci8.connection.php)
+- [@official@Database Extensions](https://www.php.net/manual/en/refs.database.php)

src/data/roadmaps/php/content/constants@VLRLymQmLfscrBfzXKvHi.md

@@ -7,4 +7,6 @@ define("PI", 3.14);
 echo PI; // Outputs: 3.14
 ```
 
-For more information, visit the PHP documentation on constants [here](https://www.php.net/manual/en/language.constants.php).
+Visit the following resources to learn more:
+
+- [@official@Constants](https://www.php.net/manual/en/language.constants.php)

src/data/roadmaps/php/content/constructor--destructor@oNUt1oT8pYBVvH0S2P6cb.md

@@ -23,4 +23,6 @@ echo $obj->value;
 // And when the script ends, "Object is being destroyed."
 ```
 
-Visit [PHP Constructors and Destructors](https://www.php.net/manual/en/language.oop5.decon.php) for a more detailed look at these vital concepts.
+Visit the following resources to learn more:
+
+- [@official@PHP Constructors and Destructors](https://www.php.net/manual/en/language.oop5.decon.php)

src/data/roadmaps/php/content/cookies@so03-fK7E2WvTm6XsPq4i.md

@@ -1,3 +1,7 @@
 # Cookies
 
-Cookies are a crucial part of state management in PHP. They enable storage of data on the user's browser, which can then be sent back to the server with each subsequent request. This permits persistent data between different pages or visits. To set a cookie in PHP, you can use the `setcookie()` function. For example, `setcookie("user", "John Doe", time() + (86400 * 30), "/");` will set a cookie named "user" with the value "John Doe", that will expire after 30 days. The cookie will be available across the entire website due to the path parameter set as `/`. To retrieve the value of the cookie, you can use the global `$_COOKIE` array: `echo $_COOKIE["user"];`. For more detailed information, you can visit [PHP's official documentation on cookies](https://www.php.net/manual/en/features.cookies.php).
+Cookies are a crucial part of state management in PHP. They enable storage of data on the user's browser, which can then be sent back to the server with each subsequent request. This permits persistent data between different pages or visits. To set a cookie in PHP, you can use the `setcookie()` function. For example, `setcookie("user", "John Doe", time() + (86400 * 30), "/");` will set a cookie named "user" with the value "John Doe", that will expire after 30 days. The cookie will be available across the entire website due to the path parameter set as `/`. To retrieve the value of the cookie, you can use the global `$_COOKIE` array: `echo $_COOKIE["user"];`.
+
+Visit the following resources to learn more:
+
+- [@official@Cookies](https://www.php.net/manual/en/features.cookies.php)

src/data/roadmaps/php/content/csrf-protection@J9yIXZTtwbFzH2u4dI1ep.md

@@ -2,7 +2,7 @@
 
 Cross-Site Request Forgery (CSRF) Protection in PHP is a method where a website can defend itself against unwanted actions performed on behalf of the users without their consent. It's a critical aspect of security as it safeguards users against potential harmful activities. Here's an example: if users are logged into a website and get tricked into clicking a deceitful link, CSRF attacks could be triggered. To protect your PHP applications from such attacks, you can generate a unique token for every session and include it as a hidden field for all form submissions. Afterwards, you need to verify this token on the server side before performing any action.
 
-```
+```php
 <?php
 // Generate CSRF token
 if(empty($_SESSION['csrf'])) {
@@ -16,4 +16,6 @@ if(isset($_POST['csrf']) && $_POST['csrf'] === $_SESSION['csrf']) {
 ?>
 ```
 
-Edge cases like AJAX requests and applications running across multiple domains require extra considerations. More about CSRF can be found in the [PHP Security Guide](https://php.net/manual/en/security.csrf.php).
+Visit the following resources to learn more:
+
+- [@official@Security Guide](https://php.net/manual/en/security.csrf.php)

src/data/roadmaps/php/content/csv-processing@MRDjEjbkMpk7shcWAoPOF.md

@@ -11,4 +11,8 @@ if (($handle = fopen("sample.csv", "r")) !== FALSE) {
 }
 ```
 
-In this snippet, PHP reads through each line of the `sample.csv` file, converting each into an array with `fgetcsv()`. You can study more about CSV processing in PHP via the official [PHP documentation](https://php.net/manual/en/ref.fileinfo.php).
+In this snippet, PHP reads through each line of the `sample.csv` file, converting each into an array with `fgetcsv()`.
+
+Visit the following resources to learn more:
+
+- [@official@CSV Processing](https://php.net/manual/en/ref.fileinfo.php)

src/data/roadmaps/php/content/curl@KC6D81-T-FwQc7Osw1rlY.md

@@ -16,4 +16,9 @@ if(curl_errno($ch)){
 
 curl_close($ch);
 ```
-In this code, we initialize a cURL session, set its options, execute it, then close the session. We also included error handling. PHP's cURL functions are documented in detail at [PHP.net](https://www.php.net/manual/en/book.curl.php).
+
+Visit the following resources to learn more:
+
+- [@official@cURL](https://curl.se/)
+- [@opensource@curl/curl](https://github.com/curl/curl)
+- [@official@cURL in PHP](https://www.php.net/manual/en/book.curl.php)

src/data/roadmaps/php/content/data-types@srIHPZabaCGdB5VvUXaMa.md

@@ -9,4 +9,6 @@ $decimalNumber = 12.34;  // Floating-point number
 $boolean = true; // Boolean
 ```
 
-For a deeper dive into PHP's data types, you can check out the official [PHP documentation](https://www.php.net/manual/en/language.types.php).
+Visit the following resources to learn more:
+
+- [@official@Data Types](https://www.php.net/manual/en/language.types.php)

src/data/roadmaps/php/content/database-migrations@meplwvmHMtI3Sb_fyodzZ.md

@@ -1,3 +1,7 @@
 # Database Migrations
 
-Database migrations help keep track of changes in your database schema, making it easier to move from one version of a database to another. Migrations allow us to evolve our database design iteratively and apply these updates across our development, staging, and production servers. This can save a lot of manual work. But more than that, migrations maintain consistency across all the environments, reducing the chances of unexpected behavior. There's no standard built-in migrations mechanism in PHP, but powerful and popular PHP frameworks like Laravel have robust solutions for migrations. Check out the [Laravel's migrations documentation](https://laravel.com/docs/migrations).
+Database migrations help keep track of changes in your database schema, making it easier to move from one version of a database to another. Migrations allow us to evolve our database design iteratively and apply these updates across our development, staging, and production servers. This can save a lot of manual work. But more than that, migrations maintain consistency across all the environments, reducing the chances of unexpected behavior. There's no standard built-in migrations mechanism in PHP, but powerful and popular PHP frameworks like Laravel have robust solutions for migrations.
+
+Visit the following resources to learn more:
+
+- [@article@Laravel Migrations](https://laravel.com/docs/migrations).

src/data/roadmaps/php/content/database-transactions@FY-F6n9j29hQrnFry3VGb.md

@@ -4,4 +4,4 @@ Database transactions in PHP refer to a unit of work performed within a database
 
 Visit the following resources to learn more:
 
-- [@official@PHP Documentation - PDO Transactions](https://www.php.net/manual/en/pdo.transactions.php)
+- [@official@PDO Transactions](https://www.php.net/manual/en/pdo.transactions.php)