Sometimes we all have a need to write instructions, or add information to an image, or combine many pictures to one. Of course you can do this using an image processing software such as Paint, GIMP, or Photoshop, but many times these are not available. And of course, what you can do in Paint is crude in the extreme, because it is a bitmap editor and not a real image editor.
Paint especially is not very good for this sort of work, because its resizing capabilities are not up to par, and whatever you insert into the picture gets inserted in it for good – revising text or moving an image in a composite are not possible. Using GIMP or Photoshop is somewhat easier due to the use of layers, which enables you to maintain texts and other adornments in editable form before you export the image, but the set of available arrows, stars, and other thingies is not very large without installing plug-ins.