Java Server Pages (JSP) allow you to separate the dynamic parts of your web pages from the static HTML. You write normal HTML code using a web page authoring tool, and then enclose dynamic code sections within special tags that mostly start with "<%" and end with "%>". JSP provides various tags like scriptlets, expressions, comments, and directives to embed Java code within web pages to add dynamic functionality. Common uses of JSP include dynamically generating content, connecting to databases to retrieve and display data, and controlling the page flow based on user input.