When using fonts, you try to pick fonts fitting to whatever design you are making. Normally, though, you don't have that many preinstalled fonts in whatever program you may use, and installing fonts is a huge pain, so instead you use css to add options for fonts, while you can't use too many since the more you have, the more the browser has to load. This is known as Google Fonts, a program created by google to greatly expand the number and types of fonts available to web designers when creating a site. As you can see below, a site I created called Jabberwocky with the font Times New Roman, Verdana, and Arial.
Next, we have the same site, just using a font called Vollkorn.
See how much better it looks just from changing the font? Next, the font used is called Libre Baskerville.
In conclusion, fonts do so much to a website, and they can either make or break a website, a website can be much worse if it was all inTimes New Roman, or even Comic Sans. So make sure you use this incredibly useful tool when in need of new, creative fonts!