Merge remote-tracking branch 'upstream/master' into 14995-custom_wiki_sidebar

* upstream/master: (4180 commits)
  Enable frozen string literals for app/workers/*.rb
  Resolve "Search dropdown hides & shows when typing"
  Revert merge request widget button max height
  Update CHANGELOG.md for 11.0.2
  Update external link icon in header user dropdown
  Added Diff Viewer to new VUE based MR page
  Fixed eslint failure in IDE spec helpers
  Use refs instead of querySelector.
  Show file in tree on WebIDE open
  Resolve "Remove unused bootstrap component CSS"
  Resolve "Explain what Groups are in the New Group page"
  [QA] Make sure we wait for the deploy key list to load
  Update _scopes_form.html.haml to remove duplicate information
  Use the branch instead of the tag to install
  port the EE changes
  Add index on deployable_type/id for deployments
  Add a helper to rename a column using a background migration
  Fix performance bottleneck when rendering large wiki pages
  Port Namespace#root_ancestor to CE
  Remove duplicate spec
  ...

1 files changed, 116 insertions, 31 deletions

diff --git a/doc/gitlab-basics/start-using-git.md b/doc/gitlab-basics/start-using-git.md
index 42cd8bb3e48..0d9994c9925 100644
--- a/doc/gitlab-basics/start-using-git.md
+++ b/doc/gitlab-basics/start-using-git.md
@@ -17,112 +17,197 @@ Depending on your operating system, you will need to use a shell of your prefere
 Git is usually preinstalled on Mac and Linux.
 
 Type the following command and then press enter:
-```
+
+```bash
 git --version
 ```
 
-You should receive a message that will tell you which Git version you have on your computer. If you don’t receive a "Git version" message, it means that you need to [download Git](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git).
+You should receive a message that tells you which Git version you have on your computer. If you don’t receive a "Git version" message, it means that you need to [download Git](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git).
 
 If Git doesn't automatically download, there's an option on the website to [download manually](https://git-scm.com/downloads). Then follow the steps on the installation window.
 
-After you are finished installing, open a new shell and type "git --version" again to verify that it was correctly installed.
+After you are finished installing Git, open a new shell and type `git --version` again to verify that it was correctly installed.
 
 ## Add your Git username and set your email
 
-It is important to configure your Git username and email address as every Git commit will use this information to identify you as the author.
+It is important to configure your Git username and email address, since every Git commit will use this information to identify you as the author.
 
 On your shell, type the following command to add your username:
-```
+
+```bash
 git config --global user.name "YOUR_USERNAME"
 ```
 
 Then verify that you have the correct username:
-```
+
+```bash
 git config --global user.name
 ```
 
 To set your email address, type the following command:
-```
+
+```bash
 git config --global user.email "your_email_address@example.com"
 ```
 
 To verify that you entered your email correctly, type:
-```
+
+```bash
 git config --global user.email
 ```
 
-You'll need to do this only once as you are using the `--global` option. It tells Git to always use this information for anything you do on that system. If you want to override this with a different username or email address for specific projects, you can run the command without the `--global` option when you’re in that project.
+You'll need to do this only once, since you are using the `--global` option. It tells Git to always use this information for anything you do on that system. If you want to override this with a different username or email address for specific projects, you can run the command without the `--global` option when you’re in that project.
 
 ## Check your information
 
-To view the information that you entered, type:
-```
+To view the information that you entered, along with other global options, type:
+
+```bash
 git config --global --list
 ```
+
 ## Basic Git commands
 
 ### Go to the master branch to pull the latest changes from there
 
-```
+```bash
 git checkout master
 ```
 
 ### Download the latest changes in the project
-This is for you to work on an up-to-date copy (it is important to do every time you work on a project), while you setup tracking branches.
+
+This is for you to work on an up-to-date copy (it is important to do this every time you start working on a project), while you set up tracking branches. You pull from remote repositories to get all the changes made by users since the last time you cloned or pulled the project. Later, you can push your local commits to the remote repositories.
+
+```bash
+git pull REMOTE NAME-OF-BRANCH
 ```
-git pull REMOTE NAME-OF-BRANCH -u
+
+When you first clone a repository, REMOTE is typically "origin". This is where the repository came from, and it indicates the SSH or HTTPS URL of the repository on the remote server. NAME-OF-BRANCH is usually "master", but it may be any existing branch.
+
+### View your remote repositories
+
+To view your remote repositories, type:
+
+```bash
+git remote -v
 ```
-(REMOTE: origin) (NAME-OF-BRANCH: could be "master" or an existing branch)
 
 ### Create a branch
-Spaces won't be recognized, so you will need to use a hyphen or underscore.
-```
+
+To create a branch, type the following (spaces won't be recognized in the branch name, so you will need to use a hyphen or underscore):
+
+```bash
 git checkout -b NAME-OF-BRANCH
 ```
 
-### Work on a branch that has already been created
-```
+### Work on an existing branch
+
+To switch to an existing branch, so you can work on it:
+
+```bash
 git checkout NAME-OF-BRANCH
 ```
 
 ### View the changes you've made
-It's important to be aware of what's happening and what's the status of your changes.
-```
+
+It's important to be aware of what's happening and the status of your changes. When you add, change, or delete files/folders, Git knows about it. To check the status of your changes:
+
+```bash
 git status
 ```
 
-### Add changes to commit
-You'll see your changes in red when you type "git status".
+### View differences
+
+To view the differences between your local, unstaged changes and the repository versions that you cloned or pulled, type:
+
+```bash
+git diff
+```
+
+### Add and commit local changes
+
+You'll see your local changes in red when you type `git status`. These changes may be new, modified, or deleted files/folders. Use `git add` to stage a local file/folder for committing. Then use `git commit` to commit the staged files:
+
+```bash
+git add FILE OR FOLDER
+git commit -m "COMMENT TO DESCRIBE THE INTENTION OF THE COMMIT"
 ```
-git add CHANGES IN RED
-git commit -m "DESCRIBE THE INTENTION OF THE COMMIT"
+
+### Add all changes to commit
+
+To add and commit all local changes in one command:
+
+```bash
+git add .
+git commit -m "COMMENT TO DESCRIBE THE INTENTION OF THE COMMIT"
 ```
 
+NOTE: **Note:**
+The `.` character typically means _all_ in Git.
+
 ### Send changes to gitlab.com
-```
+
+To push all local commits to the remote repository:
+
+```bash
 git push REMOTE NAME-OF-BRANCH
 ```
 
-### Delete all changes in the Git repository, but leave unstaged things
+For example, to push your local commits to the _master_ branch of the _origin_ remote:
+
+```bash
+git push origin master
 ```
+
+### Delete all changes in the Git repository
+
+To delete all local changes in the repository that have not been added to the staging area, and leave unstaged files/folders, type:
+
+```bash
 git checkout .
 ```
 
-### Delete all changes in the Git repository, including untracked files
-```
+### Delete all untracked changes in the Git repository
+
+```bash
 git clean -f
 ```
 
+### Unstage all changes that have been added to the staging area
+
+To undo the most recent add, but not committed, files/folders:
+
+```bash
+git reset .
+```
+
+### Undo most recent commit
+
+To undo the most recent commit, type:
+
+```bash
+git reset HEAD~1
+```
+
+This leaves the files and folders unstaged in your local repository.
+
+CAUTION: **Warning:**
+A Git commit is mostly irreversible, particularly if you already pushed it to the remote repository. Although you can undo a commit, the best option is to avoid the situation altogether.
+
 ### Merge created branch with master branch
+
 You need to be in the created branch.
-```
+
+```bash
 git checkout NAME-OF-BRANCH
 git merge master
 ```
 
 ### Merge master branch with created branch
+
 You need to be in the master branch.
-```
+
+```bash
 git checkout master
 git merge NAME-OF-BRANCH
 ```