All computer images are divided into two basic types: raster images (also known as a bitmap) and vector images.
Bitmap images are static. They are comprised of hundreds or thousands of pixels. Each pixel has a fixed position within the makeup of the bitmap. When pixels are displayed together on a computer screen, they form an image.
Vector is a synonym for the word line. Image of vector is a collection of lines and curves that connect the dots. Each node, lines and curves defined graphically by the software uses a mathematical description. Vector elements have a huge advantage to not lose quality when enlarged or reduced. For this reason, they are used mainly for print. Vector files have small size.
I have experience of using two vector programs. The first one is Microsoft Expression Design. Using it with C# and WPF, I created a game for drawing simple post cards with flowers.
I think, Illustrator is mostly known the vector drawing program. Colouring vector images a lot easier in Illustrator than in Photoshop for example. I have created a diamond firstly. I created other precious stones just by choosing all paths and changing colours of the gradient tool.