What's a "Raster Image"?
What exactly is a raster image?
For starters…it's most of the images you see on the internet! Raster image file types are static images with a fixed number of pixels. Common raster file types are PNG, JPEG, and GIF.
The downside to raster images is that, since their pixel number is fixed, they can become distorted or blurry when resized to fill a bigger space. (Have you ever gotten a warning about image quality while creating a print project? This is likely why!)
Unlike raster images, "vector" file types are made up of points and lines based on mathematical formulas that can be sized up (or down). That's why vectors are most common for graphic design! The more you know.