Images make your website look more interesting. They are the easiest way to build user engagement and increase the time users spend on your website.
However, not all website owners are photographers or graphic designers. You can’t just download and add any image to your website. Those images are probably copyrighted and can cause you trouble in the future.
Luckily, there are thousands of artists and photographers who put their work under free domain so that other people can use it. The best of these are found at paid sites like ShutterStock, but you may find other images at free sites like Pixabay, Pexels, Unsplash, PikWizard, Public Domain Pictures, or Wonderstock. Also check out https://www.chamberofcommerce.org/findaphoto/ as a tool to search multiple image sites all at once.