You can assign a flag on the message.
Every message posted to a Conversation or wall shows a flag icon that tells you instantly whether a flag is assigned on the message. For example:
If the flag icon is hollow (), then no flag is assigned on the message.
If the flag icon is not hollow ()—that is, it's a solid color, possibly with secondary marker on it—then one or more flags are assigned on the message.
There are several types of flags:
For Your Information (flag with "i")—Look at this when you have time.
Please Reply (flag with black arrow)—Look at this, and let me know what you think.
Please Reply - Urgent (flag with red arrow)—Look at this now, and let me know what you think immediately. (An email notification is always sent for Please Reply - Urgent flags.)
To get more information about a flag, you can either mouse over the flag to see a tooltip (for example, "For Your Information flag for another from Name.") or click the flag icon to see all the flag assignments.
To manage flags on an individual message: