What does the 'git add' command do in the context of staging?

'git add' prepares changes in files for commit by moving them from the working directory to the staging area. This area allows you to gather a set of changes from different files, which will then be committed together.

Usage examples:

• Add a specific file:

  git add <filename>
  

• Add all changed files (including deleted ones):

  git add -A
  

• Add all changed files (excluding deleted ones):

  git add .
  

  (or git add --all)

Without executing 'git add', changes in the working directory will not be included in the subsequent 'git commit'.

Conceptually, it can be represented as:

1. Working Directory: Your current, unstaged changes.
2. Staging Area: Changes you have prepared for the next commit.
3. Local Repository: The commit history.

graph LR
    WD -- git add --> SA
    SA -- git commit --> LR
    WD -- git reset --hard --> WD
    SA -- git restore --staged --> WD
    LR -- git checkout / git reset --> WD

• WD: Working Directory
• SA: Staging Area
• LR: Local Repository