You, as an HTML author, have no control over how a browser renders your tags. HTML 4 contains 86 markup tags. This is a sample HTML document. When encountered, the browser generates a line break. It would make no sense to have an ending tag for a line break.
Enclosure implies a beginning and end.
Some tag elements have attributes. One such tag is the image tag which is used to place an image into a document for rendering. The image tag always uses the attribute, src, to identify the source, the file name, of the image to be placed in the HTML document. The head elements bracket properties of the entire HTML document and include such things as its title and perhaps a meta tag which provides information about the document. This title is not what it appears to be.