To prevent more than one user editing a document at the same time, documents must be checked out prior to editing. Only one user can check out a document at a given time, and the user must have edit rights to the document. The check out is user- and computer-specific.

Documents that are checked out are copied to the user's local cache. The changes are updated to the server only after the document is checked in, and new documents are only saved to the server after the first check in. Documents that are checked out are not backed up on the server, so check in the documents regularly to avoid possible data loss. 

Documents that you have checked out are listed in the Checked Out to Me view in the Task pane. You can also tell the status of a document by its icon, for example:

 shows a Microsoft Word document that is checked out to you.
 shows a Microsoft Word document that is checked out to someone else.

To check out a document:

You can check out a document in multiple ways:

• Open the document from the Vault and when prompted, click Check Out.
• Right-click the document in the Vault and select Check Out.
• Select the document and click Check Out from the Task pane.
• Select the document and press <Ctrl>+O.

To check in a document:

You can check in a document in multiple ways:

• Save and close an open document.
• Right-click the document in the Vault and select Check In.
• On the Task pane, click Checked Out to Me, select the document, and click Check In.
• On the Task pane, click Checked Out to Me, select the document, and press <Ctrl>+I.

When prompted to check in the document, click Yes or No. If you do not select an answer in 15 seconds, by default your document will not be checked in.

To undo a checkout:

Right-click the document and select Undo Checkout. The new version and modifications are not saved.