Adding great images and video's to your content helps you dramatically increase engagement. Here are some free, and paid sources you can look at.
Free image downloaded at Pexels
Paid resources
Shutterstock is a paid resource for (vector) images, videos, and music
Adobe stock is an elaborate stock library which includes beautiful content in the form of (vector) images, videos, audio, 3d models, and more.
Getty Images is probably the most known stock images & video platform where you can buy content. It’s a great resource for content, both editorial, as well as creative.
iStock, owned by Getty, is another crowd-sourced stock content platform and provides original source for user-generated stock photos, vectors and illustrations, and video clips.
Free resources
Unsplash is a source of freely-usable images. Their content is user generated and often contains images that are more creative, and have a less “stock photo” look.
Pixabay is a community of creatives, sharing copyright free images and videos. All contents are released under the Pixabay License, which makes them safe to use without asking for permission or giving credit to the artist – even for commercial purposes.
Pexels, like Pixabay provides free stock photos & videos shared by talented creators. Just like Unsplash, their content is creative and doesn’t give you the feeling they are stock photos.
Flickr is an excellent resource for (vector) images, videos, and music.Flickr is user generated content so most content will have specific licences that prevent you from using it. Having said that, Flickr enables you to search for specific licences. This way you can search for “Commercial use allowed” which allows you to find content that you can use. Always double check the licence to make sure you abide by their rules.
Illustrations
unDraw: Open-source illustrations for any idea you can imagine and create.
Illustrations.co: You can download all illustrations completely free.
Opendoodles: A free set of Open-Source illustrations.