Birthday reminder using SharePoint list

If you have SharePoint 2007 and up, AND it is the enterprise version of SharePoint, then you can use what's called Information Management Policies.

1. Create a SharePoint list (custom list template) with all the people (in a people picker field) and their birthday (in a date field)
2. Create a SharePoint Designer workflow on that list, that has one action: Send an email.  Put the birthday person's name in the TO  box of the email, and make the subject and body say whatever you want. 
3. Publish the workflow.
4. Go to the list's advanced settings, and change 'allow mgmt of content types' to YES.
5. In list settings in the list of content types, there will only be one, called Item.  Click Item.
6. Click Information Management Policy settings.
7. Click "define a policy" and click OK.
8. check the box next to "enable expiration"
9. next to "a time period based on this item's properties, pick your birthday field + 1
10. next to 'perform this action" choose to run a workflow
11. Pick the name of the workflow you created at step 2

This will run every night and if it's a person's birthday they will get an email... the next day.

Reference: https://social.msdn.microsoft.com/Forums/sharepoint/en-US/e438fe69-7efa-4ee7-9660-26382611bf32/sharepoint-automatic-birthday-emails