If you're someone who uses Twitter, you've probably started to see folks posting messages with #followfriday included and then a string of Twitter addresses. Here's an example that I sent out recently:

#followfriday: Foodie edition! @offalchris @ruthreichl @richardblais @bittman @PaulKahan @hcantu @Gachatz @andrewzimmern.

Just what is this "#followfriday" phenomenon? In essence, it's a game to help others find interesting Twitter users. But before I explain how to play, let's revisit what the "hashtag," or "#" symbol does.

The “#” symbol, also called the “hashtag” in Twitter parlance, is a way to make a keyword of your choice searchable. It’s also a tool that groups of people can use to help aggregate all tweets about a particular topic.

Let’s say that you’re at a conference, and you’ve heard that the hashtag for the even is #twitcon09. This means that every tweet you post that’s related to the conference should also include #twitcon09. For example:

Evan Williams is explaining how the Twitter API works. He’ll share his presentation later online. #twitcon09

Or if there’s an upcoming event, some in the Twitter community may have already decided on a hashtag for everyone to use. During the Inauguration of President Barack Obama, the hashtag was #inaug09. Here’s a post from the day:

President Obama and the First Lady just appeared at the Neighborhood Ball. #inaug09

Hashtags are also used by the community for breaking news reports. I was in Athens, Greece, for some meetings in December 2008. The day I arrived, riots broke out in the streets. News of firebombings and attacks were actually being published on Twitter before the local media was able to report. Doing a quick search at http://search.twitter.com on “Athens riots” helped me see that the community was using #griots as the hashtag. I was on Twitter regularly for the duration of my stay so that I could follow what was happening, real-time.

A while back, someone started using the #followfriday hashtag to recommend interesting Twitterers on...you guessed it...Friday. It's a great way to share your resources and to explore who other people recommend. If you want to see everyone's #followfriday recommendations, even if you don't use Twitter yourself, click here.

Rather than suggesting general groups of people to follow, I've started to use themes every Friday. (The example above is a list of Twitterers who post about food and cooking.) You might try to do the same.

Final point of etiquette - if someone recommends you on #followfriday, it's good form to send a reply to say thanks.

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Amy Webb is a digital media consultant and head of Webbmedia Group, LLC. She has also launched Knowledgewebb, a new website for multimedia training. You can also follow Amy on Twitter and delicious. Webbmedia Group is a vendor-neutral company. Any opinions expressed about products or services are formed after testing, research and interviews. Neither Amy Webb nor Webbmedia Group or its employees receives any financial or other benefits from vendors.