All of these kinds of images are made up of discrete elements called pixels. Unfortunately, bitmaps don't change size very well and can be very data intensive. That is, they require large amounts of data to convey picture information. The DRAW programs use mathematical expressions to describe the elements, such as lines, curves and other geometries of an image. The mathematical description of a line or curve is called a vector.
Vectors are very simple primitives, but, in combination, can create extremely complex images.
Images of this type can be resized as desired without affecting resolution. And the file sizes are very small in comparison with those of bitmaps. Bezier curves, editable nodes, orthogonal snaps and graduated fills became integral parts of the artist's repertoire. One of the first utilities to become available for this new capability was the tracing function. This useful utility is available in standalone or integrated form.