feat: added core concepts page (#484)

docs/core/accounts.md

@@ -2,8 +2,6 @@
 sidebarSortOrder: 1
 sidebarLabel: Solana Account Model
 title: Solana Account Model
-altRoutes:
-  - /docs/core
 ---
 
 On Solana, all data is stored in what are referred to as "accounts”. The way

docs/core/index.md

@@ -1,5 +1,116 @@
 ---
-metaOnly: true
 title: Core Concepts
 sidebarSortOrder: 2
+description:
+  "Understanding these core concepts are very important to maximize your success
+  as a Solana blockchain developer."
 ---
+
+Build a strong understanding of the core concepts that make Solana different
+from other blockchains. Understanding the "Solana programming model" through
+these core concepts is very important to maximize your success as a Solana
+blockchain developer.
+
+## Solana Account Model
+
+On Solana, all data is stored in what are referred to as "accounts”. The way
+data is organized on the Solana blockchain resembles a
+[key-value store](https://en.wikipedia.org/wiki/Key%E2%80%93value_database),
+where each entry in the database is called an "account".
+
+Learn more about [Accounts](/docs/core/accounts.md) here.
+
+## Transactions and Instructions
+
+On Solana, we send [transactions](/docs/core/transactions#transaction) to
+interact with the network. Transactions include one or more
+[instructions](/docs/core/transactions#instruction), each representing a
+specific operation to be processed. The execution logic for instructions is
+stored on [programs](/docs/core/programs) deployed to the Solana network, where
+each program stores its own set of instructions.
+
+Learn more about [Transactions](/docs/core/transactions.md) and
+[Instructions](/docs/core/transactions.md#instruction) here.
+
+## Fees on Solana
+
+The Solana blockchain has a few different types of fees and costs that are
+incurred to use the permissionless network. These can be segmented into a few
+specific types:
+
+- [Transaction Fees](/docs/core/fees.md#transaction-fees) - A fee to have
+  validators process transactions/instructions
+- [Prioritization Fees](/docs/core/fees.md#prioritization-fees) - An optional
+  fee to boost transactions processing order
+- [Rent](/docs/core/fees.md#rent) - A withheld balance to keep data stored
+  on-chain
+
+Learn more about [Fees on Solana](/docs/core/fees.md) here.
+
+## Programs on Solana
+
+In the Solana ecosystem, "smart contracts" are called programs. Each program is
+an on-chain account that stores executable logic, organized into specific
+functions referred to as _instructions_ and called via _instruction handler_
+functions within the respective deployed program.
+
+Learn more about [Programs on Solana](/docs/core/programs.md) here.
+
+## Program Derived Address
+
+Program Derived Addresses (PDAs) provide developers on Solana with two main use
+cases:
+
+- **Deterministic Account Addresses**: PDAs provide a mechanism to
+  deterministically derive an address using a combination of optional "seeds"
+  (predefined inputs) and a specific program ID.
+- **Enable Program Signing**: The Solana runtime enables programs to "sign" for
+  PDAs which are derived from its program ID.
+
+You can think of PDAs as a way to create hashmap-like structures on-chain from a
+predefined set of inputs (e.g. strings, numbers, and other account addresses).
+
+Learn more about [Program Derived Address](/docs/core/pda.md) here.
+
+## Cross Program Invocation
+
+A Cross Program Invocation (CPI) refers to when one program invokes the
+instructions of another program. This mechanism allows for the composability of
+Solana programs.
+
+You can think of instructions as API endpoints that a program exposes to the
+network and a CPI as one API internally invoking another API.
+
+Learn more about [Cross Program Invocation](/docs/core/cpi.md) here.
+
+## Tokens on Solana
+
+Tokens are digital assets that represent ownership over diverse categories of
+assets. Tokenization enables the digitalization of property rights, serving as a
+fundamental component for managing both fungible and non-fungible assets.
+
+- Fungible Tokens represent interchangeable and divisible assets of the same
+  type and value (ex. USDC).
+- Non-fungible Tokens (NFT) represent ownership of indivisible assets (e.g.
+  artwork).
+
+Learn more about [Tokens on Solana](/docs/core/tokens.md) here.
+
+## Clusters and Endpoints
+
+The Solana blockchain has several different groups of validators, known as
+[Clusters](/docs/core/clusters.md). Each serving different purposes within the
+overall ecosystem and containing dedicated api nodes to fulfill
+[JSON-RPC](/docs/rpc/index.mdx) requests for their respective Cluster.
+
+The individual nodes within a Cluster are owned and operated by third parties,
+with a public endpoint available for each.
+
+There are three primary clusters on the Solana network, each with a different
+public endpoint:
+
+- Mainnet - `https://api.mainnet-beta.solana.com`
+- Devnet - `https://api.devnet.solana.com`
+- Testnet - `https://api.testnet.solana.com`
+
+Learn more about [Clusters and Endpoints](/docs/core/clusters.md) here.