diff --git a/git.md b/git.md
index 028b8f7..62b120c 100644
--- a/git.md
+++ b/git.md
@@ -224,3 +224,723 @@ Receiving objects: 100% (13/13), done.
 Resolving deltas: 100% (1/1), done.
 ```
 
+# 创建并切换分支
+
+```shell
+$ git checkout -b dev
+Switched to a new branch 'dev'
+//相当于以下两条命令：
+$ git branch dev
+$ git checkout dev
+Switched to branch 'dev'
+```
+
+# 查看当前分支
+
+`git branch`命令会列出所有分支，当前分支前面会标一个`*`号。
+
+```shell
+$ git branch
+* dev
+  master
+```
+
+# 合并指定分支到当前分支
+
+```shell
+$ git merge dev
+Updating 01e4329..c5dcd57
+Fast-forward
+ readme.txt | 1 +
+ 1 file changed, 1 insertion(+)
+ 
+$ git log
+commit c5dcd578aaa5f1ef323cb82231762a749af27626 (HEAD -> master, dev)
+Author: wuzhihao7 <wuzhihao7@outlook.com>
+Date:   Wed May 29 15:53:14 2019 +0800
+
+    version4 at dev
+
+commit 01e4329d253aeb75d4799594b88589301aa5ccf0 (origin/master)
+Author: wuzhihao7 <wuzhihao7@outlook.com>
+Date:   Wed May 29 14:16:54 2019 +0800
+
+    rm test.txt
+```
+
+用带参数的`git log`也可以看到分支的合并情况：
+
+```shell
+$ git log --graph --pretty=oneline --abbrev-commit
+*   2513abd (HEAD -> master) merge with no-ff
+|\
+| * d7ee6d2 (dev) version 6 at dev
+|/
+*   deb15a8 conflict fixed
+|\
+| * 0a93f24 version 5 at feature1
+* | f6b1271 version 5 at master
+|/
+* c5dcd57 version4 at dev
+* 01e4329 (origin/master) rm test.txt
+* 978cffb add test.txt
+* d24b6fe version3
+* 72b87bd version2
+* e4ad803 add readme.txt
+
+```
+
+# 删除分支
+
+```shell
+$ git branch -d dev
+Deleted branch dev (was c5dcd57).
+```
+
+# 解决冲突
+
+```shell
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master)
+$ git merge feature1
+Auto-merging readme.txt
+CONFLICT (content): Merge conflict in readme.txt
+Automatic merge failed; fix conflicts and then commit the result.
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master|MERGING)
+$ git status
+On branch master
+Your branch is ahead of 'origin/master' by 2 commits.
+  (use "git push" to publish your local commits)
+
+You have unmerged paths.
+  (fix conflicts and run "git commit")
+  (use "git merge --abort" to abort the merge)
+
+Unmerged paths:
+  (use "git add <file>..." to mark resolution)
+
+        both modified:   readme.txt
+
+no changes added to commit (use "git add" and/or "git commit -a")
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master|MERGING)
+$ less readme.txt
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master|MERGING)
+$ less readme.txt
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master|MERGING)
+$ vi readme.txt
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master|MERGING)
+$ git status
+On branch master
+Your branch is ahead of 'origin/master' by 2 commits.
+  (use "git push" to publish your local commits)
+
+You have unmerged paths.
+  (fix conflicts and run "git commit")
+  (use "git merge --abort" to abort the merge)
+
+Unmerged paths:
+  (use "git add <file>..." to mark resolution)
+
+        both modified:   readme.txt
+
+no changes added to commit (use "git add" and/or "git commit -a")
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master|MERGING)
+$ git add readme.txt
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master|MERGING)
+$ git status
+On branch master
+Your branch is ahead of 'origin/master' by 2 commits.
+  (use "git push" to publish your local commits)
+
+All conflicts fixed but you are still merging.
+  (use "git commit" to conclude merge)
+
+Changes to be committed:
+
+        modified:   readme.txt
+
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master|MERGING)
+$ git commit -m "conflict fixed"
+[master deb15a8] conflict fixed
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master)
+```
+
+合并分支时，加上`--no-ff`参数就可以用普通模式合并，合并后的历史有分支，能看出来曾经做过合并，而`fast forward`合并就看不出来曾经做过合并。
+
+```shell
+$ git merge --no-ff -m "merge with no-ff" dev
+Merge made by the 'recursive' strategy.
+ readme.txt | 1 +
+ 1 file changed, 1 insertion(+)
+
+$ git log
+commit 2513abd9036b00e047b56b547db9c2d1f7fea2ab (HEAD -> master)
+Merge: deb15a8 d7ee6d2
+Author: wuzhihao7 <wuzhihao7@outlook.com>
+Date:   Wed May 29 16:41:35 2019 +0800
+
+    merge with no-ff
+
+commit d7ee6d22841778acedd353b9ac74d8f41f22bfed (dev)
+Author: wuzhihao7 <wuzhihao7@outlook.com>
+Date:   Wed May 29 16:40:28 2019 +0800
+
+    version 6 at dev
+```
+
+# 把当前工作现场“储藏”起来，等以后恢复现场后继续工作
+
+```shell
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (dev)
+$ git status
+On branch dev
+Changes not staged for commit:
+  (use "git add <file>..." to update what will be committed)
+  (use "git checkout -- <file>..." to discard changes in working directory)
+
+        modified:   readme.txt
+
+no changes added to commit (use "git add" and/or "git commit -a")
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (dev)
+$ git stash
+Saved working directory and index state WIP on dev: d7ee6d2 version 6 at dev
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (dev)
+$ git status
+On branch dev
+nothing to commit, working tree clean
+
+$ git stash list
+stash@{0}: WIP on dev: d7ee6d2 version 6 at dev
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (dev)
+$ git stash apply stash@{0}
+On branch dev
+Changes not staged for commit:
+  (use "git add <file>..." to update what will be committed)
+  (use "git checkout -- <file>..." to discard changes in working directory)
+
+        modified:   readme.txt
+
+no changes added to commit (use "git add" and/or "git commit -a")
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (dev)
+$ git stash list
+stash@{0}: WIP on dev: d7ee6d2 version 6 at dev
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (dev)
+$ git stash drop stash@{0}
+Dropped stash@{0} (8510bcf5ce3ccc1cac49ef860ce48707a0600d8e)
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (dev)
+$ git stash list
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (dev)
+$ git status
+On branch dev
+Changes not staged for commit:
+  (use "git add <file>..." to update what will be committed)
+  (use "git checkout -- <file>..." to discard changes in working directory)
+
+        modified:   readme.txt
+
+no changes added to commit (use "git add" and/or "git commit -a")
+```
+
+用`git stash apply`恢复，但是恢复后，stash内容并不删除，你需要用`git stash drop`来删除；
+
+另一种方式是用`git stash pop`，恢复的同时把stash内容也删了
+
+可以多次stash，恢复的时候，先用`git stash list`查看，然后恢复指定的stash，用命令：
+
+```
+$ git stash apply stash@{0}
+```
+
+# 强行删除未合并的分支
+
+```shell
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master)
+$ git branch -d dev
+error: The branch 'dev' is not fully merged.
+If you are sure you want to delete it, run 'git branch -D dev'.
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master)
+$ git branch -D dev
+Deleted branch dev (was 62270ec).
+```
+
+# 查看远程库的信息
+
+```shell
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master)
+$ git remote
+origin
+
+wuzhihao@WuZhihao MINGW64 /c/job/learngit (master)
+$ git remote -v
+origin  git@github.com:wuzhihao7/learngit.git (fetch)
+origin  git@github.com:wuzhihao7/learngit.git (push)
+```
+
+# 推送分支
+
+推送分支，就是把该分支上的所有本地提交推送到远程库。推送时，要指定本地分支，这样，Git就会把该分支推送到远程库对应的远程分支上：
+
+```shell
+$ git push origin master
+```
+
+如果要推送其他分支，比如`dev`，就改成：
+
+```shell
+$ git push origin dev
+```
+
+但是，并不是一定要把本地分支往远程推送，那么，哪些分支需要推送，哪些不需要呢？
+
+- `master`分支是主分支，因此要时刻与远程同步；
+- `dev`分支是开发分支，团队所有成员都需要在上面工作，所以也需要与远程同步；
+- bug分支只用于在本地修复bug，就没必要推到远程了，除非老板要看看你每周到底修复了几个bug；
+- feature分支是否推到远程，取决于你是否和你的小伙伴合作在上面开发。
+
+# 拉取分支
+
+多人协作时，大家都会往`master`和`dev`分支上推送各自的修改。
+
+现在，模拟一个你的小伙伴，可以在另一台电脑（注意要把SSH Key添加到GitHub）或者同一台电脑的另一个目录下克隆：
+
+```shell
+$ git clone git@github.com:michaelliao/learngit.git
+Cloning into 'learngit'...
+remote: Counting objects: 40, done.
+remote: Compressing objects: 100% (21/21), done.
+remote: Total 40 (delta 14), reused 40 (delta 14), pack-reused 0
+Receiving objects: 100% (40/40), done.
+Resolving deltas: 100% (14/14), done.
+```
+
+当你的小伙伴从远程库clone时，默认情况下，你的小伙伴只能看到本地的`master`分支。不信可以用`git branch`命令看看：
+
+```shell
+$ git branch
+* master
+```
+
+现在，你的小伙伴要在`dev`分支上开发，就必须创建远程`origin`的`dev`分支到本地，于是他用这个命令创建本地`dev`分支：
+
+```shell
+$ git checkout -b dev origin/dev
+```
+
+现在，他就可以在`dev`上继续修改，然后，时不时地把`dev`分支`push`到远程：
+
+```shell
+$ git add env.txt
+
+$ git commit -m "add env"
+[dev 7a5e5dd] add env
+ 1 file changed, 1 insertion(+)
+ create mode 100644 env.txt
+
+$ git push origin dev
+Counting objects: 3, done.
+Delta compression using up to 4 threads.
+Compressing objects: 100% (2/2), done.
+Writing objects: 100% (3/3), 308 bytes | 308.00 KiB/s, done.
+Total 3 (delta 0), reused 0 (delta 0)
+To github.com:michaelliao/learngit.git
+   f52c633..7a5e5dd  dev -> dev
+```
+
+你的小伙伴已经向`origin/dev`分支推送了他的提交，而碰巧你也对同样的文件作了修改，并试图推送：
+
+```shell
+$ cat env.txt
+env
+
+$ git add env.txt
+
+$ git commit -m "add new env"
+[dev 7bd91f1] add new env
+ 1 file changed, 1 insertion(+)
+ create mode 100644 env.txt
+
+$ git push origin dev
+To github.com:michaelliao/learngit.git
+ ! [rejected]        dev -> dev (non-fast-forward)
+error: failed to push some refs to 'git@github.com:michaelliao/learngit.git'
+hint: Updates were rejected because the tip of your current branch is behind
+hint: its remote counterpart. Integrate the remote changes (e.g.
+hint: 'git pull ...') before pushing again.
+hint: See the 'Note about fast-forwards' in 'git push --help' for details.
+```
+
+推送失败，因为你的小伙伴的最新提交和你试图推送的提交有冲突，解决办法也很简单，Git已经提示我们，先用`git pull`把最新的提交从`origin/dev`抓下来，然后，在本地合并，解决冲突，再推送：
+
+```shell
+$ git pull
+There is no tracking information for the current branch.
+Please specify which branch you want to merge with.
+See git-pull(1) for details.
+
+    git pull <remote> <branch>
+
+If you wish to set tracking information for this branch you can do so with:
+
+    git branch --set-upstream-to=origin/<branch> dev
+```
+
+`git pull`也失败了，原因是没有指定本地`dev`分支与远程`origin/dev`分支的链接，根据提示，设置`dev`和`origin/dev`的链接：
+
+```shell
+$ git branch --set-upstream-to=origin/dev dev
+Branch 'dev' set up to track remote branch 'dev' from 'origin'.
+```
+
+再pull：
+
+```shell
+$ git pull
+Auto-merging env.txt
+CONFLICT (add/add): Merge conflict in env.txt
+Automatic merge failed; fix conflicts and then commit the result.
+```
+
+这回`git pull`成功，但是合并有冲突，需要手动解决，解决的方法和分支管理中的解决冲突完全一样。解决后，提交，再push：
+
+```shell
+$ git commit -m "fix env conflict"
+[dev 57c53ab] fix env conflict
+
+$ git push origin dev
+Counting objects: 6, done.
+Delta compression using up to 4 threads.
+Compressing objects: 100% (4/4), done.
+Writing objects: 100% (6/6), 621 bytes | 621.00 KiB/s, done.
+Total 6 (delta 0), reused 0 (delta 0)
+To github.com:michaelliao/learngit.git
+   7a5e5dd..57c53ab  dev -> dev
+```
+
+# rebase
+
+多人在同一个分支上协作时，很容易出现冲突。即使没有冲突，后push的童鞋不得不先pull，在本地合并，然后才能push成功。
+
+每次合并再push后，分支变成了这样：
+
+```
+$ git log --graph --pretty=oneline --abbrev-commit
+* d1be385 (HEAD -> master, origin/master) init hello
+*   e5e69f1 Merge branch 'dev'
+|\  
+| *   57c53ab (origin/dev, dev) fix env conflict
+| |\  
+| | * 7a5e5dd add env
+| * | 7bd91f1 add new env
+| |/  
+* |   12a631b merged bug fix 101
+|\ \  
+| * | 4c805e2 fix bug 101
+|/ /  
+* |   e1e9c68 merge with no-ff
+|\ \  
+| |/  
+| * f52c633 add merge
+|/  
+*   cf810e4 conflict fixed
+```
+
+在和远程分支同步后，我们对`hello.py`这个文件做了两次提交。用`git log`命令看看：
+
+```
+$ git log --graph --pretty=oneline --abbrev-commit
+* 582d922 (HEAD -> master) add author
+* 8875536 add comment
+* d1be385 (origin/master) init hello
+*   e5e69f1 Merge branch 'dev'
+|\  
+| *   57c53ab (origin/dev, dev) fix env conflict
+| |\  
+| | * 7a5e5dd add env
+| * | 7bd91f1 add new env
+...
+```
+
+注意到Git用`(HEAD -> master)`和`(origin/master)`标识出当前分支的HEAD和远程origin的位置分别是`582d922 add author`和`d1be385 init hello`，本地分支比远程分支快两个提交。
+
+现在我们尝试推送本地分支：
+
+```
+$ git push origin master
+To github.com:michaelliao/learngit.git
+ ! [rejected]        master -> master (fetch first)
+error: failed to push some refs to 'git@github.com:michaelliao/learngit.git'
+hint: Updates were rejected because the remote contains work that you do
+hint: not have locally. This is usually caused by another repository pushing
+hint: to the same ref. You may want to first integrate the remote changes
+hint: (e.g., 'git pull ...') before pushing again.
+hint: See the 'Note about fast-forwards' in 'git push --help' for details.
+```
+
+很不幸，失败了，这说明有人先于我们推送了远程分支。按照经验，先pull一下：
+
+```
+$ git pull
+remote: Counting objects: 3, done.
+remote: Compressing objects: 100% (1/1), done.
+remote: Total 3 (delta 1), reused 3 (delta 1), pack-reused 0
+Unpacking objects: 100% (3/3), done.
+From github.com:michaelliao/learngit
+   d1be385..f005ed4  master     -> origin/master
+ * [new tag]         v1.0       -> v1.0
+Auto-merging hello.py
+Merge made by the 'recursive' strategy.
+ hello.py | 1 +
+ 1 file changed, 1 insertion(+)
+```
+
+再用`git status`看看状态：
+
+```
+$ git status
+On branch master
+Your branch is ahead of 'origin/master' by 3 commits.
+  (use "git push" to publish your local commits)
+
+nothing to commit, working tree clean
+```
+
+加上刚才合并的提交，现在我们本地分支比远程分支超前3个提交。
+
+用`git log`看看：
+
+```
+$ git log --graph --pretty=oneline --abbrev-commit
+*   e0ea545 (HEAD -> master) Merge branch 'master' of github.com:michaelliao/learngit
+|\  
+| * f005ed4 (origin/master) set exit=1
+* | 582d922 add author
+* | 8875536 add comment
+|/  
+* d1be385 init hello
+```
+
+输入命令`git rebase`：
+
+```
+$ git rebase
+First, rewinding head to replay your work on top of it...
+Applying: add comment
+Using index info to reconstruct a base tree...
+M	hello.py
+Falling back to patching base and 3-way merge...
+Auto-merging hello.py
+Applying: add author
+Using index info to reconstruct a base tree...
+M	hello.py
+Falling back to patching base and 3-way merge...
+Auto-merging hello.py
+```
+
+输出了一大堆操作，到底是啥效果？再用`git log`看看：
+
+```
+$ git log --graph --pretty=oneline --abbrev-commit
+* 7e61ed4 (HEAD -> master) add author
+* 3611cfe add comment
+* f005ed4 (origin/master) set exit=1
+* d1be385 init hello
+...
+```
+
+原本分叉的提交现在变成一条直线了！这种神奇的操作是怎么实现的？其实原理非常简单。我们注意观察，发现Git把我们本地的提交“挪动”了位置，放到了`f005ed4 (origin/master) set exit=1`之后，这样，整个提交历史就成了一条直线。rebase操作前后，最终的提交内容是一致的，但是，我们本地的commit修改内容已经变化了，它们的修改不再基于`d1be385 init hello`，而是基于`f005ed4 (origin/master) set exit=1`，但最后的提交`7e61ed4`内容是一致的。
+
+这就是rebase操作的特点：把分叉的提交历史“整理”成一条直线，看上去更直观。缺点是本地的分叉提交已经被修改过了。
+
+最后，通过push操作把本地分支推送到远程：
+
+```
+Mac:~/learngit michael$ git push origin master
+Counting objects: 6, done.
+Delta compression using up to 4 threads.
+Compressing objects: 100% (5/5), done.
+Writing objects: 100% (6/6), 576 bytes | 576.00 KiB/s, done.
+Total 6 (delta 2), reused 0 (delta 0)
+remote: Resolving deltas: 100% (2/2), completed with 1 local object.
+To github.com:michaelliao/learngit.git
+   f005ed4..7e61ed4  master -> master
+```
+
+再用`git log`看看效果：
+
+```
+$ git log --graph --pretty=oneline --abbrev-commit
+* 7e61ed4 (HEAD -> master, origin/master) add author
+* 3611cfe add comment
+* f005ed4 set exit=1
+* d1be385 init hello
+...
+```
+
+远程分支的提交历史也是一条直线。
+
+# 标签管理
+
+## 创建标签
+
+在Git中打标签非常简单，首先，切换到需要打标签的分支上：
+
+```
+$ git branch
+* dev
+  master
+$ git checkout master
+Switched to branch 'master'
+```
+
+然后，敲命令`git tag <name>`就可以打一个新标签：
+
+```
+$ git tag v1.0
+```
+
+可以用命令`git tag`查看所有标签：
+
+```
+$ git tag
+v1.0
+```
+
+默认标签是打在最新提交的commit上的。有时候，如果忘了打标签，比如，现在已经是周五了，但应该在周一打的标签没有打，怎么办？
+
+方法是找到历史提交的commit id，然后打上就可以了：
+
+```
+$ git log --pretty=oneline --abbrev-commit
+12a631b (HEAD -> master, tag: v1.0, origin/master) merged bug fix 101
+4c805e2 fix bug 101
+e1e9c68 merge with no-ff
+f52c633 add merge
+cf810e4 conflict fixed
+5dc6824 & simple
+14096d0 AND simple
+b17d20e branch test
+d46f35e remove test.txt
+b84166e add test.txt
+519219b git tracks changes
+e43a48b understand how stage works
+1094adb append GPL
+e475afc add distributed
+eaadf4e wrote a readme file
+```
+
+比方说要对`add merge`这次提交打标签，它对应的commit id是`f52c633`，敲入命令：
+
+```
+$ git tag v0.9 f52c633
+```
+
+再用命令`git tag`查看标签：
+
+```
+$ git tag
+v0.9
+v1.0
+```
+
+注意，标签不是按时间顺序列出，而是按字母排序的。可以用`git show <tagname>`查看标签信息：
+
+```
+$ git show v0.9
+commit f52c63349bc3c1593499807e5c8e972b82c8f286 (tag: v0.9)
+Author: Michael Liao <askxuefeng@gmail.com>
+Date:   Fri May 18 21:56:54 2018 +0800
+
+    add merge
+
+diff --git a/readme.txt b/readme.txt
+...
+```
+
+可以看到，`v0.9`确实打在`add merge`这次提交上。
+
+还可以创建带有说明的标签，用`-a`指定标签名，`-m`指定说明文字：
+
+```
+$ git tag -a v0.1 -m "version 0.1 released" 1094adb
+```
+
+用命令`git show <tagname>`可以看到说明文字：
+
+```
+$ git show v0.1
+tag v0.1
+Tagger: Michael Liao <askxuefeng@gmail.com>
+Date:   Fri May 18 22:48:43 2018 +0800
+
+version 0.1 released
+
+commit 1094adb7b9b3807259d8cb349e7df1d4d6477073 (tag: v0.1)
+Author: Michael Liao <askxuefeng@gmail.com>
+Date:   Fri May 18 21:06:15 2018 +0800
+
+    append GPL
+
+diff --git a/readme.txt b/readme.txt
+```
+
+## 操作标签
+
+如果标签打错了，也可以删除：
+
+```
+$ git tag -d v0.1
+Deleted tag 'v0.1' (was f15b0dd)
+```
+
+因为创建的标签都只存储在本地，不会自动推送到远程。所以，打错的标签可以在本地安全删除。
+
+如果要推送某个标签到远程，使用命令`git push origin <tagname>`：
+
+```
+$ git push origin v1.0
+Total 0 (delta 0), reused 0 (delta 0)
+To github.com:michaelliao/learngit.git
+ * [new tag]         v1.0 -> v1.0
+```
+
+或者，一次性推送全部尚未推送到远程的本地标签：
+
+```
+$ git push origin --tags
+Total 0 (delta 0), reused 0 (delta 0)
+To github.com:michaelliao/learngit.git
+ * [new tag]         v0.9 -> v0.9
+```
+
+如果标签已经推送到远程，要删除远程标签就麻烦一点，先从本地删除：
+
+```
+$ git tag -d v0.9
+Deleted tag 'v0.9' (was f52c633)
+```
+
+然后，从远程删除。删除命令也是push，但是格式如下：
+
+```
+$ git push origin :refs/tags/v0.9
+To github.com:michaelliao/learngit.git
+ - [deleted]         v0.9
+```
+
+要看看是否真的从远程库删除了标签，可以登陆GitHub查看。
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