Why do I change the tags name, but the explore still could show well like <p>?

Like teacher or other where to say, you need to follow the html rules, you need to follow what they told you that use the correctly tags name. If not,

Like teacher or other where to say, you need to follow the html rules, you need to follow what they told you that use the correctly tags name. If not, the printout will not show correctly. But when I randomly change the tags name to or the web still show ok, same as use

tags, please tell me the reason. If it's in the explore has default think if a character has a "<>" if we couldn't understand it, we will treat it like

.

Or if we use any other tags when we use in the css or javascript it will not work well. Please tell me the reason, Hope somebody help me. Thank you.

or:Like teacher or other where to say, you need to follow the html rules, you need to follow what they told you that use the correctly tags name. If not, the printout will not show correctly. But when I randomly change the tags name to or the web still show ok, same as use

tags, please tell me the reason. If it's in the explore has default think if a character has a \"<>\" if we couldn't understand it, we will treat it like

.Or if we use any other tags when we use in the css or javascript it will not work well. Please tell me the reason, Hope somebody help me. Thank you.

Tags:html,rules,