If you have a Spreadsheet with multiple sheets, you’ll see the ID at the end of the URL changes as you move to different sheets.
If we select the second worksheet: Sheet2
we can see that the final part of the URL has changed to give us
Worksheet ID: /edit#gid=1183988251
Further to this, if you use Filter Views in your Sheet they also get a unique URL, adding a further part:
Filter View ID: &fvid=1287889739
If you want to link someone to a specific sheet you can copy and paste the URL so it will open on your chosen sheet. You can use these URLs in an email or chat message to a colleague to send them exactly where you want, creating a customised view for different users.