Tags are your personal classification system for mail messages and contacts, and are an aid to finding those items. For example, you might have one tag for Immediate Turnaround and another for Medium Priority. The mail messages that are tagged can be in different folders, and the tags provide a way to show all messages with a certain tag, wherever they are..
You can create as many tags as you want.
You can apply multiple tags to the same mail message and contacts.
You can access the New Tag feature in any of the following ways:
From anywhere, click the down arrow next to New and choose Tag.
Select Tag from the toolbar.
Right-click an item in a list view and choose Tag Conversation or Tag Message > New Tag.
Right-click on Tags or a tag in the Overview Pane and choose New Tag.
A New Tag dialog appears. Enter a name and click OK. Tag names can have any character except the following
: (colon)
/ (forward slash)
" (double quotes)
The new tag is listed under Tags in the Overview Pane and can be applied to any mail messages or contacts.