In Aras terminology, when you "Lock" an item like a Document, you reserve it such that only you can edit it. Only one person at a time can lock any given item. When you "Unlock" the item, you make it available for others to potentially lock and edit. The ability to lock items is controlled by Aras permissions. For example, permissions for most users are set such than when an item is in Preliminary (in-work) state, it can be locked, but when it is in Released state, it cannot be locked and therefore cannot be edited.
The Office Connector uses the lock and unlock function to control who has the rights to edit files. The lock status is indicated by the "Locked by" field in the ribbon; if this is showing a name, then the Document is locked, and if not, it is unlocked. If it is showing your name, then you have edit rights to the file.
The Office Connector automates much of the lock and unlock behavior in ways that is intuitive when working on your Office files. This includes:
So if you just remember to use Save and Close when you are done editing, the system will basically take care of proper locking and unlocking.
At any time you can also use the Lock or Unlock commands in the ribbon, depending on the current state of the Document. If currently unlocked, you may use Lock and this will give you editing rights. If currently locked, you may use Unlock and this will remove editing rights. Note that if you have made local changes to a file and then use Unlock, the system will prompt you if it is OK to lose local changes or not.