Phoca Photo is Joomla! CMS component - it displays images on Joomla! site. It includes categories view (list of categories), category view (list of images) and image view. It does not include any administration features (images and categories should be managed by Phoca Gallery). It includes only frontend views, which load the content fast and easy on the site.
It is a Bootstrap alternative to Phoca Gallery output which is created by flexbox.