Images can be included in your presentations to demonstrate and ease understanding of discussion points.
Be aware though that copyright protection also applies to images, photographs and graphics, and that theses protections are more meaningful as we usually want to use the whole work.
The following sources include images that are expected to be re-used by others, with appropriate acknowledgement.
Always check the licence arrangements and select "use with attribution" or attribution free sites.
The following video explains why Creative Commons licences exist and the differences between them. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
University of Guelph (2018) What are Creative Commons licenses? Available at: https://youtu.be/srVPLrmlBJY (Accessed: 22 September 2022).