Wikipedia:Tip of the day/January 7
For images, there are free tools like GIMP and ImageMagick, and commercial ones like Adobe Photoshop that provide a variety of processing filters. The preferred formats are Scalable Vector Graphics (SVG) for drawings, and Portable Network Graphics (PNG) for pictures. You may also use JPEG.
Vector graphics are preferred to raster graphics for drawings, because they can be scaled as needed without losing information, and because they can be more easily edited. Please remember to follow our guidelines and policies when uploading images.