Inkscape is vector graphic editor. File extension of Inkscape file is SVG or Scalable Vector Graphic. What is a vector and why it is scalable? You may have no idea what it is, but you can see this illustration for an example. Vector image based on geometric while bitmap graphic based on pixel. Main benefit is, vector graphic is scalable without reducing its quality.

Compare to bitmap graphic, if you scale it to larger or smaller size, the result is annoying image because you scale pixel not image. You can expand or shrink from original size without losing any of thefidelity of the original image. If you still want to have a bitmap image when you’re done, it’s easy to convert an SVG image to a bitmap. This is called rasterization. Just export SVG image to .png or .jpg file. Although it is easy to go from vector to bitmap, it’s not easy to go from bitmap to vector.