Discussion links are links to web-based message boards where your readers can talk about your entries. Some blogs don't bother with discussions, while others are defined by the communities in their discussion areas. Some blogs have a different discussion area for each post, others have a single Ür-message-board with a long running discussion about the posts on the front page.
Depending on which blog tool you use to maintain your blog, you may have to use a third-party service to host your discussions. On Boing Boing, we use QuickTopic (http://www.quicktopic.com/), creating a new topic for each post. Some blogging tools have message boards built in. With Movable Type, for example, you just check a box labeled Allow Comments when you're creating your post, and Movable Type automatically generates a new discussion board and puts a link to it on your post. Likewise, Radio UserLand has an automated facility for adding discussion boards to blog entries.
Discussion boards can be a vital part of a healthy blog. They transform your blog from a broadcast into a conversation, where you and your readers can discuss the items you post. Be warned, though: message boards abstract discussion away from the social cues that we use when we talk face-to-face. Decent people can be breathtakingly abusive on a message board. A single jerk can ruin a fruitful discussion with persistent bile. If you run a blog, you will eventually attract such a jerk (a "troll" in Internet parlance), and he will make your life absolutely miserable.
When confronted with a troll, you have three immediate temptations:
To argue back, meeting fire with fire
To delete the offending post
To shut down the message board entirely
Resist these temptations. Arguing back is fruitless. Internet trolls live to engage otherwise sane people in pointless, heated debate. Deleting the post sets up an arms race, where your troll returns again and again, assuming new identities, until you find yourself spending all your time hunting down and eliminating offensive posts, while your blog idles away, untended and static. Deleting the message board altogether satisfies the troll's victory condition: he has silenced your readers with his vitriol.
Take a lesson from free speech advocates: the answer to bad speech is more speech. Ignore your troll (and encourage your readers to do the same), while you continue to have your discussion. Trolls really do disappear if no one pays them any attention. Some message boards have email gateways, allowing you to read and post from your mail client. If your message board has this option, use it and avail yourself to your mailer's filters and delete the troll's posts unread.
