Inkscape is a great free program for creating vectors (scalable graphics that won't blur when you resize them)). It's so good, in fact, that it's a serious alternative to premium tools like Adobe Illustrator.
Why you need it
Adobe has a dominant position in the image software world, but that doesn't mean there aren't excellent alternatives.
Create and edit SVG files
Fully anti-aliased display
Create and edit vector graphics
is one such program – an open source vector imaging suite that mounts a serious challenge to Adobe's Illustrator. What's more, Illustrator is £17.50, US$19.99, AU$22.99 per month, whereas Inkscape is totally free.
But don't think it's a pared-back, limited offering. Inkscape comes with all sorts of tools for manipulating and creating vector graphics.
You can manipulate image shapes, fill them with gradients, apply filters, group them with other layers, convert them to paths, distort them and so much more. There's not enough space to list everything that Inkscape can do, which just attests to how powerful it is.
Simply put, if you can do it in Illustrator, chances are you can do it in Inkscape, and that's pretty incredible for a piece of free vector software. If nothing else, give it a try to see how you find it; if it's not for you, you haven't lost a thing.