Front-End Design
Well, in the simplest terms, front end could refer to the UI layer of websites, you know, the things that people see and interact with. Back end usually describes the processes that happen on the server that helps make things work. Client side and server side generally refer to the same things and are often used interchangeably with front and back end.
CSS
CSS, or Cascading Style Sheets, is a style sheet language developed to control the presentation of HTML documents. Over the years HTML has evolved into a semantic language. Meaning that the language focuses on identifying elements and defining document structure, not on how those elements should be presented or formatted. For that we have CSS. As the name implies, cascading style sheets are a collection of formatting rules usually contained in an external file. They can control a range of pages from a single page to entire websites.
Client-Side Scripting With JavaScript
JavaScript is a scripting language used in web design to add interactivity and application functionality to sites. It was created in 1995 by Netscape to increase the capabilities of its popular browser. Contrary to popular belief, JavaScript has absolutely nothing to do with the programming language Java. Netscape actually licensed the term Java from Sun to speed up the acceptance of their new scripting language.
What Is An API
APIs, or Application Programming Interfaces, are written to provide a set of instructions and standards for using a specific service. They're usually written to make it easier for developers to use an application or to make services publicly available to anyone who wants to use them.
Web Fonts
For years, the only way to display fonts on your site, was to use the fonts installed on the client machine. That meant that you really couldn't use just any font that you want, you had to rely on system fonts that were widely distributed with popular operating systems. This is why we've become so familiar with reading websites in Arial, Verdana, or Georgia. And recently, that has all changed, with the evolution and support of web fonts. So how do web fonts differ from how we've traditionally used fonts? Technically, the term web fonts refers to any technology that allows the automatic downloading and temporary installation of fonts on the client. Since that's mainly accomplished using the CSS @font-face rule, the term web fonts has begun to simply refer to the @font-face technique. But it is important to note that the SVG font face element allows this functionality as well.