top-post: v. To put the newly-added portion of an email or Usenet response before the quoted part, as opposed to the more logical sequence of quoted portion first with original following. The problem with this practice is neatly summed up by the following FAQ entry:
Q: Should I include quotations after my reply?
bottom-post: v. In a news or mail reply, to put the response to a news or email message after the quoted content from the parent message. This is correct form, and until around 2000 was so universal on the Internet that neither the term ‘bottom-post’ nor its antonym top-post existed. Hackers consider that the best practice is actually to excerpt only the relevent portions of the parent message, then intersperse the poster's response in such a way that each section of response appears directly after the excerpt it applies to. This reduces message bulk, keeps thread content in a logical order, and facilitates reading.