Typography is the way your text looks on a page, including factors such as Fonts, Size, Colours and Weight.
Typefaces and Fonts
Typefaces and Fonts are terms often used by Designers but what do they mean? Well, Typeface is a term used for a family of Fonts (Helvetica Regular, Helvetica Italic, Helvetica Black and Helvetica Bold). Helvetica would be the Typeface and all the variations of the Helvetica Font make up the Typeface. Fonts are a term used for one style used within a Typeface/Family (Helvetica Black).
It is best practice to limit the number of fonts used on a webpage. The use of 3 or more fonts makes the site look unprofessional and untidy.
Contrast and Colours
Colours on a webpage should look appealing and draw a user in. Ensuring the Typography on the page, is in contrast with the background, making it easy to read is key to do this. The best example of this is Black Text on a White Background or White Text on a Black Background. These colours are complete opposites making the text easy to read. Looking at the image below, you can see that the top two rows are hard to read, the third is a little easier but the bottom is very clear.