It's always important to give credit to the sources you used to help you create your final product, whether it's an essay, slideshow, website, or infographic. Giving credit is the fair thing to do, and it also shows all of the awesome research and thought you put into your work. It's the same thing as when a music artist gives "feat" or "ft" credit to another musician who is in their song or video.

Putting things in your own words is one of the most challenging parts of doing research. It can be hard to imagine that you can improve on the words of a professional writer, especially if you're not an expert on a subject.