Marking mail for follow-up in mail.app

Hello...

I did a search but could not find anything anywhere on this...I am trying to "flag" an email so that I know that I need to follow up on it in the next little while -- how do I do that in mail.app -- I have been using Outlook for the last 10 or so years and I am used to "flagging" emails there...is there anything similar in mail.app?

Any insight would be greatly appreciated...

select an email, right-click on it, mark>as flagged.

or, select an email, go to the Message menu, then mark>as flagged.