But what is a vector? And how can you quickly identify a vector file? Here's what you should know. What is a vector file? Again, there are generally two types of images you'll see online and in apps, rasters (also known as bitmaps) and vectors. The distinction between them can seem complicated, but is actually quite simple. Raster graphics are made of a grid of pixels, each one of which is assigned a precise color. Vectors, on the other hand, are built from mathematically defined shapes like lines and curves. This means that vector graphics can be infinitely resized without losing any sharpness or color quality, which is great for projects that need high quality images.