.PHOTOLIBRARY File Extension
File TypeiPhoto Photo Library
What is a PHOTOLIBRARY file?
Library of digital photos created by iPhoto, an image organization application; contains all of the images that appear in your iPhoto application along with the edits that have been made to them; created whenever you add another library in iPhoto.
iPhoto is an photo organization and editing application developed by Apple. The program enables you to crop, enhance, and touch-up your images. It also makes it easy to share your photos to to social sites like Facebook, Twitter, and Flickr.
NOTE: iPhoto was discontinued and replaced by Photos in 2015.