The header is the top block of a web page that typically contains a logo with a link to the homepage, the company's name, contact information, and a site search form. It may sometimes include the main navigation menu if it's more convenient to place it horizontally and visually separate it from the content. In some cases, this block may be absent or reduced to a minimal presence since it's not a mandatory element.
Sometimes, the header is referred to as the "header," which can be translated from English as the "top header." Practically, on any webpage, you will come across the HTML <head> tag, inside which you can find the page title, meta tags, a description of the stylesheet, and linked files.