Internal links: An internal link is a link from one web page on your blog, to another web page ,also on your blog. These are very useful since they can help lead your visitors to other related relevant material on your site.
An external link is a link from a web site other than your own, which points to a page on your site.
Hypertext is the visible text which is linked to another post.
The more links you have within your website and, more importantly pointing to your website, the more successful your website will be.