Tags are basically markers that enclose text, images, links, etc. In fact, it's a good idea to keep more than one browser around for testing purposes. A web server is needed so that your pages can be viewed by the world. A server is not needed to create a page. Tags HTML is composed of tags.
Tags typically occur in begin-end pairs.
These pairs define containers. Any content within a container has the rules of that container applied to it. HTML is also not sensitive to line breaks, carriage returns, and white space. If this is missing or in a wrong place the start tag's properties will be carried through the entire document. This concept is not too difficult and should be easy to master.