Imagine you're telling your best friend that you have just met the love of your life. Finally, you'd get around to describing all the little details like exactly what you said and exactly what he or she said, and so forth. There's a practical reason for the inverted pyramid format, too. Editors editing news stories often have to make the story a particular length so that it will into a predetermined amount of space in the newspaper. Furthermore, they often have to do so under severe deadline pressure.
Speed is highly important.
If a story is written in inverted pyramid format, the editor can simply trim the story one paragraph at a time, going from the bottom up, until the story is the right length. The editor can do so confidently, knowing that even though information is being cut from the story, it is being cut in ascending order of importance. Once you get the hang of the inverted pyramid format, you'll find it has all kinds of uses. Journalists use it, but it's not just for journalists.