'Tagging' a photo is a way to indicate who is in a photo on Geni. You can tag a photo while viewing that photo or during the photo upload process.
To tag a photo that has already been uploaded to Geni, click the 'edit' link next to 'In this photo' under the photo. Start typing the name of the person that is in the photo to select the person with the people tagger.
Repeat this process for each person in the photo. When you have added the name of each person in the photo click done.
You may also use the People Identifier by clicking on the photo directly. You will then be able to choose a name from the list.
While both will methods tag the photo with the person's name - only the People Identifier will place a green square around the face of the person.
This photo will now be associated with each person you tagged. If this is the first photo tagged with a person's name this will be their profile photo. The most recently tagged photo for each person will be displayed on their profile.
Profile ID trick
To tag someone who is outside of your Friend and Family Groups, you can use their Profile ID. The Profile ID is the string of numbers at the end of the URL when viewing their Profile. Paste this number instead of their name when tagging a photo and click the 'search more' link to tag them.
Related link: How to Upload Photos on Geni.com (YouTube video)