What does Heading Tags mean?
These can sometimes be confused with meta tags but they are completely different.
Heading tags relate to the visible text on the page and help tell search engines what that page is about.
The easiest way to understand them is to imagine that your website is a book and each page is a chapter. So each page should have a title. This is your <h1/> tag.
In the code for this page we have
<h1>What does Heading Tags mean?</h1>
The <h1> and <h1> are totally invisible to the reader but they tell the search engines that this is the predominant theme of the page.
You then get subheadings. The text "Sub headings" above this paragraph is actually written in the code:
The '2' indicates this is the second most important title.
You should only ever have one <h1> tag in the same way that a chapter should have only one title but you can have as many <h1>s, <h2>s, <h3>s, etc. as you like.
Be careful however to make sure that the headings and subheadings are balanced with a reasonable amount of text. Pages where the majority of text is in headings and subheadings will be treated with suspicion.
Nesting Heading Tags
Nesting is basically where you make sure all <h3>s are within <h2>s and so on. Getting this wrong is a very common mistake, especially when using an application such as WordPress. Here people often choose heading types because they look good and have the size of text they want but underneath, in the code, it becomes a mess like this:
<h2>Visitor center opening hours</h2>
<h1>Make sure you also visit our Cafe!</h1>
For a search engine it is confusing. The main title is within the 4th subheading and the 2nd subheading comes before any title. It's difficult to read and make sense of and so it's difficult to know where to rank the page in search results.
When headings don't matter
You may have noticed some pages on the internet have completely different text in their heading tags compared to what they are ranking for. Heading Tags are a part of SEO, not all of it.
If users search for a keyword, go to a website and stay on that website, search engines must conclude that page is about that keyword - regardless of what is said in the heading tags!