Tweet - The only question that drives Twitter is "What are you doing?" and a Tweet is a response to that question. If you are into social networking sites like Facebook and Orkut or even a Skype or GTalk user, you must already know what the status message means. But unlike the other services, the status message on Twitter i.e. the Tweet is not a passive message but the medium of communication or the counter-part of the IM you send to your chat buddy. However, a Tweet is generally visible universally unless, of course you have blocked a person. A Tweet can be of 140 character length only, which could be one of the reasons why Tweets travel faster than anything else i know of.
Handle - Username, this is important as it is likely to become your identity on Twitter, for example my Twitter handle is danishctc. You can find my profile on twitter by simply typing http://twitter.com/danishctc in the location bar or your browser. You can also reply me or mention it by simply prefixing my handle with the @ (at) symbol : @danishctc
DP - Stands for display picture or avatar. It is highly recommended that you put up your own picture as DP.
RT: Retweet is nothing but the same tweet being posted again by another user. There could be many reasons for doing this but the most common ones are- the person liked the particular tweet and would like to share it with her/his followers and the original Tweet is kept to make sure that the response is seen in the context. To retweet, you can copy the whole tweet along with the original tweeterer's handle (prefix the @ (at) symbol to the handle ) and type RT right at the beginning. (Most clients make this easy, explained here just to make sure)
Screenshot of my convo with de3p , pushkarbhatt
Replies/Mentions: these are tweets by other users who have either replied,addressed or mentioned your handle. A handle prefixed by @(at) symbol is treated by Twitter as a tweet meant for that particular person and shows up on his timeline; for example- "danishctc: @anandmisra hi"
"danishctc: D anandmisra this a dm"
Friends - Twitter is people-driven, if you want to harness its power then you have to follow people whose updates you would want see. You could start following people in the suggested list that Twitter displays when you sign up or celebrities you already know ( for example Shashi Tharoor, Celina Jaitly, Gul Panag) but it is important that you find other like-minded users to make your tweeting productive. As with so many services, Twitter can also import your contact list from other accounts and suggest your pre-existing contacts that are already on Twitter. To follow them you can go to their profile page and click on the link "Follow" (Note: Following a large number of people in a very short time is seen suspiciously by Twitter since spam bots seem to follow a similar pattern, trying interacting as much as possible )
Followers - These are people who are following your updates. They are important from your point of view since they are your main audience as well as customer-base.
Favorites- If you find a particular tweet interesting and dont want to lose it in the melee, you can add it to your favorites. To add a Tweet to favorites, click on the star icon, the Tweet can now be found in the favorite section of your Twitter profile.
One of the major advantages of Twitter is the fact that it is not limited to a single client, single domain or even single device. I prefer tweeting from mobile rather than the desktop.
The original interface for interaction was Twitter.com and continues to be so since that is where you manage your account and set preferences. This is also the site you should be using if you are a new user.However, this interface lacks certain features for more advanced users but this is aptly compensated by numerous third-party clients.
Clients- There are plenty of clients avaible, download the one which meets your expection. On desktop/laptop, i find Tweetdeck the best, followed by Twhirl and Seesmic. Firefox add-on, Twitter Fox is another client that i find myself using a lot. On mobile (i use Nokia N95 8GB), Gravity comes across as the client with best features but i have also used Fring and Twibble for tweeting.
There also some very cool web-based clients that you should check out: http://dabr.co.uk and http://slandr.com
Update - Thanks to Softykid for reminding me about Snaptu, a mobile client that i had heard a lot about yet never got to installing it. But now that i have done it, it is strongly recommended that you try it out :)
P.S.: Thats it for now, hope someone finds it useful coz i didn't get much pleasure compiling it! not my kinda thing ;)
The Twitter Song