Is there a Name for this Style of Capitalisation?

It seems quite common on the web to capitalise certain words in a heading, or navigation bar, but not others.

Here are some examples:

Visit the Member's Page

How to Format (as seen on this very website)

Create a Corporate Themed Website with our Tutorial

To me it seems any "important" words are capitalised, and words such as and, of, to, from are not. Is that the case? If so, is there a name or term for this behaviour?

This is generally only seen in titles of web pages, or headings perhaps, and not something I've seen commonly in the body of a piece of text.

It's called "title case":

Among U.S. book publishers (but not newspaper publishers), it is a common typographic practice to capitalize "important" words in titles and headings. This is an old form of emphasis, similar to the more modern practice of using a larger or boldface font for titles. Most capitalize all words except for closed-class words, or articles, prepositions and conjunctions. Some capitalize longer prepositions such as "between", but not shorter ones. Some capitalize only nouns, others capitalize all words. This family of typographic conventions is usually called title case.

Here are some related questions:

• Which words in a title should be capitalized?
• When should you use “Title Case”?

Lastly, capitalizing all words in a title is called "start case".