check out option is available in all SharePoint libraries.
Use it when you want to prevent other users from:
seeing your changes in a file before you are ready
to show them.
editing the same file as you are working with yourself.
A checked out file is locked for editing to everyone else
but the person who checked out the file, and as long
as this editor remembers to check in the file again when
he has finished editing the feature works well.
In the demo below Peter Kalmström, CEO and Systems Designer
of kalmstrom.com Business Solutions, shows how you can check
out and check in a file and how the file is marked when
checked out. Peter also explains how you can set check out
to mandatory before editing and discusses benefits and drawbacks
of doing so.