What is this thing called "Joiner"

Well - might look a little daft - a bit like a badly drawn photo collage - but in reality - Ive set it this way - a new thing Ive learned about in college.
Idea is to photo something in minute detail - put them together (hence "Joiner" I suspect!!!)into a new view of the desired object.
Another way of doing things - an example by the august Hockney = Blossom Highway?
Ill have to try fitting in a link!