What images can I use in my work, my school papers, on my blog etc.? This is a recurring question. The answer is not always easy. It can depend on several things, including which country you are in. But you can of course always use images that you have produced yourself. That includes photos that you take with your phone or a camera, and anything you draw or paint. Most often you may not want to do this, but you are looking for something that already exists to illustrate a text, a presentation or something else you are writing or designing.
You can always use images that are in the public domain. Images are released into the the public domain either because they are old enough or because the person who owns the rights to the image has decided to release it into the public domain. If you are a teacher, a student or is thinking about making your work public in another capacity it is wise to choose images which are free and legal to use. Public domain resources are a good option here. You can also use work licensed under Creative Commons.
Some useful sites for images