If you haven't spent much time on Twitter, you may not know what hashtags are, but if you're trying to sell ebooks, it's definitely something you want to learn. When people tweet, you'll notice there are often words in the tweet text or appended to the end of the tweet which are preceded by the pound sign—you know, this thing: #. It's the character above three on your keyboard, also known as the hash or number symbol. In Twitter, the hash sign before a word indicates that the word is a search term for that tweet, in much the same way as tags are used for articles, blog posts, or products on Amazon (see my article on book tagging for more on that topic). When a tweeters use hashtags, they helps searchers locate tweets that are relavent to what they're searching for.

For example, whenever I tweet about ebooks or ebook readers in general or about my book in particular, I append one or more of these hashtags to the text of the tweet: #ebook, #ebooks, #kindle, #nook, #writing, or #authors, as tweet space allows. People who are searching for information about any of these, can search within Twitter or on Twitter-related sites like Twubs, Twibes, or Topsy for all tweets with the given hashtag. The hashtag system turns the overwhelming mish-mash of sound bites that is Twitter into a useful, organized directory of information.

A particular hashtag that every ebook author should be aware of is "#samplesunday". This tag is the brainchild of author David Wiseheart, who first proposed its use on his blog, "Kindle Author". The purpose of #samplesunday is to allow authors to post excerpts of their writing on their blogs or websites, and then tweet about them with the hashtag #samplesunday. If you use #samplesunday, you should also search for other authors' #samplesunday tweets, read their excerpts, comment on them, and of course, retweet them, as they will do the same in return. It's a quick and easy way to get a sample of your work into the hands of those who are looking for something new to read for the week.

I've tried out #samplesunday a number of times, and it always increases traffic to my blog, so I highly recommend it as a free book marketing method. Why not try it yourself this week?