Don't do JPGs!

Summary - use PNG or TIFF to save your images, not JPG, especially if you have text

Please note - any photos you take with a camera that save as JPGs will be ok - this post only really applies to images you make yourself

The most common format for images is JPG compression, which, when used wisely is relatively harmless. However, used inconsiderately, it can cause extreme pain to your eyes. Consider, for example, the following peacock...

Familiar, yes? But anyway, aside from the slight out of focusness, the quality is quite good, the edges are edges, and so on. It is, all in all, a rather appealing use of the JPG format. However! JPG images can be compressed to different degrees upon saving, and this one has been saved at about 10 (out of 12, although some editors will measure it out of 100). Let us see what happens if we slide that down to 1.

Oh dear...not nice at all. The background is covered in squares, and the beak has just been mangled. However, you aint seen nothing yet. Let's add some text...

And I think you get the idea.

Moral of the story is don't do JPGs, kids!
unless that is, you know where the quality slider bar is. There is an easier solution though! Use other lossless formats such as TIFF or PNG (when you select Save As when saving whatever it is you are saving, there should be a dropdown box underneath the file name box). These will generate enormous files, but we can compress them when we get them whilst checking the quality.