The HTML programming language was conceived and designed as early as 1991, which was several years before the Internet's famed debut in modern culture in the mid-nineties. Internet historians point to a publication by Tim Berners-Lee that introduced a small handful of the most basic HTML tags as the closest point to the "birth" of the world wide web, though HTML's earliest forms were initially produced as examples of Standard Generalized Markup Language. By the time HTML 5 had been established, however, the language had deviated enough from SGML that web browsers could no longer parse them through the same interpretative process.
At any rate, the 1991 document offers a window into the earliest structural trends of HTML and makes evident not only how foreign many incredibly basic syntactic concepts came across to technicians at the time but also how many concepts that would later become "common knowledge" simply did not exist. For example, the earliest HTML documents were not even divided into "head" and "body" sections; only the "title" tag existed to mark a particular segment of the source code as separate from the content within the body. The document explained the relevance of the six header tags that are in use even to this day, but its introductory explanation of list-based syntax evidently placed responsibility on the author to manually input either bullets to create an unordered list or numbers to make an ordered list.
The earliest HTML tags include concepts that are modestly used nowadays such as the "description list" series of tags, which group short titles with longer and indented descriptions underneath them. They also include tags that were deleted prior to HTML 2.0 such as the "Highlighted Phrase" tags, which appeared to be a method of defining whether the enclosed text was bold, italic, or both. The original incarnation of HTML also included an esoteric "IsIndex" tag that was a precursor to modern HTML forms in how it produced a text field that could accept a text query. This was intended to be used for searching for other pages on the website. For more information click here https://www.webdesignmuseum.org/web-design-history/tim-berners-lee-published-a-document-called-html-tags-1991.