When we code in HTML, CSS, JS, etc. we are communicating to the browser. That’s what we do as web designers. We are telling the browser how to display content. The browser understands many different languages. It understands, HTML, CSS, JavaSript, XML, SVG and others. Each of those languages have their own syntax. For the browser to interpret the languages correctly we have to tell the browser which language we are using.
For example, when we link an external stylesheet, the browser is expecting to see only CSS characters in the .css file. We link it as <link rel="stylesheet" type="text/css" href="someFileName.css">. We are telling the browser that we are linking a file that has a relationship to the HTML file as a stylesheet and is using text characters that should be interpreted as CSS code. The browser is expecting something very specific. If you give it something other than what it is expecting, you will get errors.
The > character does exist in CSS, but it doesn’t mean the same thing as it does in HTML.