Using the "more" tag to split blog articles
From Spiffy Stores Knowledge Base
When you write your article, you can insert a <!--more--> tag after the first paragraph, or after the first few sentences. This tag will be used to display only the text above this tag on the Blog page. This gives a quick summary of all the articles and allows the reader to click on the article link to read the full article, if they are interested.
For example, These lines give an introduction to the article. <!--more-->
Now, continue with more detail in the article.
Note: In the new WYSIWYG Editor, the <!--more--> must be inserted in code view, or you can use the page break icon, which inserts it for you.