What is Archive, What is 'All Mail'?

All Mail is your archive, a storage place for all the mail you've ever sent or received, but have not deleted.

You can see a list of archived messages by clicking All Mail. Archived messages are also available by searching, and under any assigned labels.

To archive mail:

1. Select the message(s) you'd like to archive by checking the box(es) next to the sender's name.
2. Click Archive at the top of your inbox.

You also can archive mail after you open it -- just click Archive along the top of the message