Heading Tag
A "Heading tag" is a headline at the top of a website article, a sub heading, or other similar text on a webpage. There are several sizes of Heading tags, but all Heading tags are always set in a larger font from the body text (the main text on a page). Heading tags are highly recommended for SEO purposes. Properly used, Heading tags will help search engines find and categorize your webpage, thereby increasing web traffic.
So how do Heading tags increase your website's search engine ranking? Many search engines consider a Heading tag as more important text than the body text, and consider Heading tags as keywords. For this reason, search engines give heading tags much more weight than other body text.
Because of the way Heading tags are written into the coding for the webpage, search engines are able to pick out Heading tags from other text. They give priority to Heading text over all other text displayed on a webpage. Search engines don't give priority to other (non-Heading) text that's displayed in large or bold fonts, even if the text looks the same on the webpage as heading text (such as if text is laid out as a headline but it isn't designated as a Heading tag).
A Heading tag is designated in the HTML code the webpage is created with, and not merely by using Cascading Style Sheets or a larger font. Not all browsers recognize Cascading Style Sheets (CSS). Ideally, writing the Heading tag into the HTML code allows all browsers to uniformly display the webpage's Heading tag in the desired size, and in the designated place. Some browsers may not always display Heading tags the same way, however, and this is the reason you should always view your website on all the main browsers to make sure text is displayed in the right way and it is working properly.
Heading tags should be written and used like newspaper headlines: a Heading tag should state the subject of the article or portion of text, so readers know if this is something they want to read. Well-written Heading tags are brief summaries of the text that follows them, in the same way that good email or text message subject titles sum up the gist of a message.
There are five sizes of Heading tags, called simply Heading 1, Heading 2, Heading 3, Heading 4, and Heading 5. Heading 1 is the largest sized Headline, with the text sizes decreasing proportionally to Heading 5, which is the smallest Headline text. The Heading tags are all displayed in bold. The Heading tag's actual display font size as seen on the computer screen will depend upon the individual computer user's preferences.
Remember, it doesn't matter if you set portions of the main body text are in big type or small. They will not be read by search engines as "Heading text." In order to get more "ranking power" text has to be marked as Heading text in the HTML programming itself.