As long as you have a date of birth entered for a client and have enabled the Reminder for their Birthday, a Reminder will show up on the Reminders tab of your Today page:
A green banner will show up horizontally across the top of each page of their contact records as well on their actual birthday:
You can determine how early birthdays show up in your Reminders and how long they stay there after the date has passed under Manage Your Account —> Change Site Preferences in the Dashboard Reminders section:
You can enable or disable Birthday Reminders for your contacts by clicking Edit in their Contact Details and then checking or unchecking "Enable Reminder" next to Date of Birth:
Of course you can also enable or disable Birthday Reminders in bulk from your Advanced Search page. You can run a search on the DOB reminder field to bring up a list of those that fall in either camp. Then, from your Contact Options / Bulk Actions menu you'll find that you have the ability to Change Birthday Reminders in bulk.
Birthday Reminders can come in handy if you want to handpick the clients whose birthdays actually show up in your Reminders section. You may send birthday cards to all of your clients, but there may be only a select group that you want to show up in this Reminders section, e.g. those that you would like to personally call on their birthday.
While the Birthday Reminders will be visible for all of your database users, you may want to utilize Redtail's Advanced Search in order to run Labels for Birthday Cards or to run Birthday Reports. Toward the end of each month, you can run an Advanced Search on the upcoming month's Birthdays. As an example, let's say it's nearing the end of August and you want to pull up all September birthdays for your clients.
After running this search, you'll see a list of all of your clients with September birthdays entered in your database. You can then run Labels for Birthday Cards or produce a Birthday Report from the Reports menu, which you can then print out and refer to throughout the month.