Check In and Check Out a File / List Item in SharePoint
Checking documents in and out can be done from a Microsoft Office application, but since not all documents are Office based it is more consisted to use check in and check out from the web interface.
To check out a file or list item simply navigate to the document or list item and hover the mouse over the file/item and then select Check Out:
This will check the file/item out and prevent other users modifying it while you are editing it. When checking out files (but not list items) using Internet Explorer you will be asked if you want to check out the file to a local drafts folder. If you select OK, a copy of the file is placed in a special folder named SharePoint Drafts in your My Documents folder. If you do not choose this option the file is just marked as checked our to you but a local copy is not made. The SharePoint Drafts folder allows you to use and edit the file locally.
To Check In the file / list item, navigate back to the file / list item , hover the mouse over it and select Check In – this will automatically upload the file / item to the SharePoint site.
Checking in a file increments the version number (the amount of the increment depends on the settings for the list or document library).