This is what is called a "lemon" or "nimbu" in India, Nepal, & Pakistan-
|The small but flavorsome Desi 'lemon' or nimbu.|
No, it is not like the bright yellow, thick skinned, oblong shaped, almost bitterly sour citrus fruits called "lemons" in the western world.
|The 'western' idea of a lemon.|
The Desi lemon or nimbu is much smaller, round, usually greenish in hue, thin skinned, with a sour yet slightly sweet & pleasant floral flavor much like what is called a 'Key lime' in the US.
Do not use the yellow 'western' type of lemon in place of a Desi lemon/nimbu, you will be bitterly disappointed (pun intended). Rather use a lime if you can't find a Desi lemon/nimbu, or better yet a Key lime to get the same taste.