What is the purpose of documentary photography?

Communication: We took a photo, but if I just took it and put it on the hard disk, it would be meaningless. Photography is only half finished, and it won't be finished until you show it to others and cause others (your readers) to react accordingly. It's like those photos I took more than ten years ago. Now I'll show them and show them to you. The reader's "thinking reaction" can be varied. After seeing your photos, they may be happy, perhaps inexplicably lost, or perhaps they are filled with emotion after smiling.