If you have a blog or other website, your choice of fonts and how you style the text can make a big difference not only in how attractive your site looks, but also its readability. This interactive guide can quickly teach you what you need to know about typography.
Created by web designer and developer Tommi Kaikkonen, the Interactive Guide to Blog Typography covers layout, visual hierarchy, fonts, colour, and more. The explanations are short and simple, and several topics have buttons where you can play around with different choices.
For further, more in-depth instruction, you'll want to take a look at typography manuals and other design resources, but this short guide is a great start.