One of the personal items needed when creating a Facebook account is your date of birth (aka DOB). Except for younger people who want to circumvent the minimum age requirement of Facebook most enter their real information.
When viewing someone’s information, their DOB is visible. Many do not want others to know their age. However, the month and day make it possible to easily send a birthday message to friends on their day.
Here is how to hide your birth year:
Sign in to your Facebook account. If you are not at your page, click the profile picture next to your name in the title bar.
Click the About tab.
Mouse over the section to the right of the About window to expose the Edit your contact and basic info link and click it.
Scroll down to BASIC INFORMATION Birth Year and click the Edit button that appears to the right of the year.
To the right of the lock, click the down-arrow to pull down the selection.
Select Only me and you will be the only one that can view your birth year. This does not stop Facebook from letting others know it is your birthday but it will not show them how old you are.
Click Save Changes.
I hope this helps your experience on Facebook and perhaps you can pass this tip on to others.