You may flag an account, opportunity or activity (only in the web version) whenever it is important to you, whether you are the owner or not, and, if for any reason, you want to recevie notifications from these or when modifications are made on these or their related elements (for example: events in the caledar, offers, opportunities etc....).

If for example, you flag and account, you will receive a notification and an email to inform you whenever a check-in is made, an activity is added (type of comment, call...), a new opportunity is created or when the details of the account or any of its related activites are modified.
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