What are those vertical lines next to the number of code line

Question

What exactly are these lines used for and what's the name of the extension?

Glandular

Start by looking what extensions you have installed in VSCode. See if any fit the bill. – Bothy

These lines indicate changes. Blue lines indicate modifications and green lines indicate additions. They are added by VCS extensions like Git. – Casing

Every time you see one of these things I suggest you move your mouse pointer over it. More often than not, you get a tooltip, pane or clickable area that often clarifies its purpose. – Incumber

if you click on them you get a peek-window with a diff for this region – Collative

Answer 1

These lines indicate changes in the file. Blue lines indicate modifications (line of code was modified), green lines indicate additions (line of code was added) and red lines indicate deletions (line of code was deleted). They are added by version control system (VCS) extensions like Git.

You can find a similar image with similar line on https://code.visualstudio.com/docs/editor/versioncontrol

That's the built-in VCS for Git.

Casing

Okay, I haven't installed anything in the VS Code which would cause something like this. I found the image on google and want to know the extension name? By any chance, do you know? – Glandular

@Glandular VSCode has a built-in extension for Git. Is this a Git project? A common extension is Gitlens – Casing

NO, It's just a random image I found on google. I haven't had anything like this in my editor? How can I make it work on my editor? – Glandular

@Glandular It only works in Git projects. The extension indicates which lines have changed since the last commit. It won't work without VCS. – Casing

Okay, Thank you :) – Glandular

@Glandular You can find a similar image on code.visualstudio.com/docs/editor/versioncontrol – Casing

OH Okay, I got it. – Glandular

Answer 2

Theses lines is controlled by setting in Settings -> Features -> Source Control -> "Diff Decorations".

You can change many options (can disable, click action, etc.)

Webbing

"Diff Decorations Gutter" they are. – Leapt