Free Vector Files
Vector files are great because they are made of lines and shapes. Actually, they are made up of instructions of dots and lines, producing crisp and smooth shapes.
You can open them in Photoshop (or many other image editing software) and define the size. You can then use these shapes in your design.
Tutorial Blog.org has compiled a big list of free vector files for download. I didn’t have to think twice to bookmark this site.