High quality content (such as blog posts and articles) can benefit from having images included, though for most of us buying stock photography isn't an option for every single blog post. For that, we have free stock photo websites. For ‘free' you ask? Completely free. Free as in: you use the picture however you want to (as long as you don't claim it's your own), for personal or business use.
I use stock images a lot (or I doodle something) so having access to a large variety of images is super important to me. For that I've been compiling a list of high quality sources to get completely free stock photography.
As I'm constantly updating this list I've made it into a spreadsheet for easy management. You can access this sheet on Google Drive here: