Staging area (index) purpose in Git - Step-by-Step Execution

Process Flow - Staging area (index) purpose

Working Directory

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Add files to Staging Area (Index)

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Commit from Staging Area to Repository

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Repository stores committed snapshots

Changes are first made in the working directory, then added to the staging area (index), and finally committed to the repository.

Execution Sample

Git

git add file.txt
git commit -m "Save changes"

Add changes of file.txt to staging area, then commit them to the repository.

Process Table

Step	Action	State of file.txt	Staging Area (Index)	Repository
1	Modify file.txt in working directory	Modified content	Empty	Last committed version
2	Run 'git add file.txt'	Modified content	file.txt staged with new content	Last committed version
3	Run 'git commit -m "Save changes"'	Modified content	Empty after commit	file.txt updated with new content
4	End	No new changes	Empty	file.txt latest committed version

💡 No more changes to commit; staging area cleared after commit

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
file.txt in Working Directory	Committed version	Modified content	Modified content	Modified content	Modified content
Staging Area (Index)	Empty	Empty	file.txt staged	Empty	Empty
Repository	file.txt committed	file.txt committed	file.txt committed	file.txt updated	file.txt updated

Key Moments - 2 Insights

Why do changes need to be added to the staging area before committing?

Because the staging area lets you select exactly which changes to include in the next commit, as shown in step 2 of the execution_table.

What happens to the staging area after a commit?

It is cleared, meaning no files are staged anymore, as shown in step 3 and 4 of the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, what is the state of the staging area after running 'git add file.txt'?

A Empty

B file.txt staged with new content

C file.txt committed

D file.txt deleted

💡 Hint

Check the 'Staging Area (Index)' column at Step 2 in the execution_table.

At which step does the repository get updated with the new file content?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Repository' column in the execution_table to see when it changes.

If you modify file.txt but do not run 'git add', what will the staging area contain?

A Empty

B file.txt committed

C file.txt staged with new content

D file.txt deleted

💡 Hint

Refer to Step 1 in the execution_table where the file is modified but not added.

Concept Snapshot

Staging area (index) holds changes you want to commit.
Use 'git add' to stage changes.
Commit saves staged changes to repository.
Staging area lets you control commit content.
After commit, staging area clears.

Full Transcript

In Git, when you change files, those changes first happen in your working directory. To prepare these changes for saving, you add them to the staging area, also called the index, using 'git add'. This area holds exactly what will go into your next commit. When you run 'git commit', Git takes the staged changes and saves them permanently in the repository. After committing, the staging area is cleared, ready for new changes. This process lets you carefully select which changes to save and when.