Every page on our wiki has an associated talk page (a.k.a. a discussion page). This is a feature of the Mediawiki software we use.
Each of these pages exists for people in our wiki community to talk over what belongs on the page it supports. For instance, if you wanted to totally restructure the Wiki tool shed page, you might bring up your proposed changes on the talk page (Talk:Wiki tool shed) first, and see how other people like the idea.
In addition, every person who makes an account on the site also has a talk page of their own. User talk pages have a special feature: if you leave somebody a message on their own page, the next time they log in they will see a bright banner at the top of the screen informing them they have a new message. (Or if they're already logged in, they'll see the note the next time they click on a new page.)
Some points of possible confusion
We make heavy use of redirects on this wiki. Redirects are very helpful, especially to newcomers; every time the end user types in a phrase that is redirected, she arrives at the page she's looking for, bypassing a list of search results.
"Talk" vs. "Discussion"
In different places, the Mediawiki refers to these places as "talk pages" or as "discussion pages." We inherit this inconsistency.