Almost every computer comes with a set of pre-installed fonts, and these core fonts are pretty much the same on Windows and on Mac OS X. This is good, because designers can specify these commonly available fonts, and feel “safe” that most site visitors will have those fonts.
But designers often feel restricted by the narrow choices of web-safe fonts such as Times, Arial, and Georgia, and often specify their text with the much larger selection of fonts available through web-font services.
Some of these services are free of charge, while others require a subscription fee. The designer decides which font(s) he wants to use, enters some relatively simple code into his site, and when a visitor comes to the website, the web-font service downloads the correct fonts to the browser.
Use an external style sheet when you want to apply the same styles consistently across some or all pages in your web site. By defining styles in external style sheets, and linking them to pages, you ensure consistency of appearance throughout those pages. If you decide to change a style, you need to make only one change – in the external style sheet – and the change will be reflected in all pages that are linked to that style sheet. Typically, an external style sheet uses the .css file name extension, such as in “sitestyle.css.”
Cascading Style Sheets (CSS) is a style-sheet language used for describing the look and formatting of a document written in HTML.
CSS is designed primarily to enable the separation of the HTML document content from the document presentation, including elements such as the layout, colors, and fonts.
—if you’re looking for the easy way out already, you should consider not using web fonts. If you don’t know what web fonts are doing to improve your design, they may not be right for you. – Zach Leatherman.