A social unit composed of parents and their children (at least one).
Family members don't need to be biologically related. In case one of the parents is deceased, this tag may be used with only one parent and their children.
Additionally, grandparents and extended family may be included in the image, but only if the family itself is complete. Complete being all living parents and their children.
When it's only a single parent with one child use the following tags instead:
Pixiv
Twitter
Bluesky
Weibo
Lofter
Tumblr
