The difference between vector and raster graphics is that raster graphics are composed of pixels, while vector graphics are composed of paths. A raster graphic, such as a gif or jpeg, is an array of pixels of various colors, which together form an image.
Your logo represents your brand and is used across a wide range of media: your website, business cards, flyers, banners, etc. Ensure a consistent and crisp display in all contexts by having it in vector format.