WordPress makes a distinction between pages and posts when it comes to publishing content. From a coding perspective, there is very little difference between pages and posts. Probably the only difference is the way their tagged. But from a user experience perspective, both the publishers and readers, experience pages and posts differently.
The pages of your website most likely consist of more stable forms of information. That is, the content on your website that doesn’t change, is more likely to be in a page. And when the information does change, then you edit the page. Contact Us is most often a page.
The content that you want to publish and leave unchanged, like a snapshot from a certain date, is content for a post. Events make good posts. You wouldn’t edit a captain’s log and you don’t generally edit your posts either. Your web log is an online journal and these archives become valuable repositories of old information.