Flash is a multimedia development technology, allowing for interactive multimedia applications to be embedded in web documents. Flash can often add rich engaging content to a website, but is considered very search engine un-friendly.
For an SEO driven website, flash must unfortunately, be avoided. Embedded audio and video found on websites (like youtube) are often flash-driven.
Also known as boards, discussion boards, message boards, or discussion forums, forums are collections of community-driven discussions. Forum software solutions vary greatly, but often a forum offers topics with threaded conversations, and require contributors to register an account in order to take place in discussions. Forums are similar to email mailing list discussions, and bulletin boards.
Often targeted towards one topic or niche, forums are usually meant to be places of polite discourse between like-minded people. Often one or multiple community members are appointed moderators, and they police the forum, to make sure users and discussions follow forum rules.
In addition to being a great way to form a community around a website, a forum can provide great content for a search engine to index, sending additional traffic to a website.
Frames are a HTML display option that allows more than one document to be displayed in the same window. These days, frames are often discouraged, partly due to the fact that search engines do not properly crawl pages implemented with frames. A frames based website is a bad design decision when you are building a search engine friendly website.
FTP stand for File Transfer Protocol, and is an Internet protocol designed for sending files to and from servers. Websites are often updated by interacting with the web server through FTP.