Traditionally, when you write, you start with a 'foundation' and gradually build to a conclusion in a pyramid style. You might write an essay or article using the following structure:
Problem statement
Related work
Methodology
Results
Conclusions
Journalists, on the other-hand, use an inverted pyramid style. They generally start with the main conclusion and get progressively more detailed, like so:
Conclusion
Supporting information
Background and technical details
Since Web users typically scan text, it is important to position main points at the beginning of the article, then go into more detail as needed.