To understand what Unschooling is, it helps to understand what it is not. It can also help to see some of the best examples. Please follow a few links and compare these things to what you already know and have learned from your own childhood, experiences, and observations.

Relaxed Homeschooling vs. Unschooling
Lisa W.'s list of what relaxed homeschoolers might do (have done) that unschoolers probably wouldn't, and Ren Allen's response to the same question!

The Difference between Schooling and Unschooling
Rebecca Justus made this list on the Unschooling.Info forum, and I formatted it and enshrined it.

Is there a difference between a Radical Unschooler and just an Unschooler?

Getting it
People describing the differences between when they first thought they understood and when they knew they really did.

Living by Principles instead of by Rules

Marginal Unschooling
Just barely there? Bad examples.

Criticism of Unschooling

All Kinds of Homeschooling
1998 article by Sandra Dodd

All of those articles have links to next-step or related or contrasting things. Explore! Decide you want to learn, go forth and soak it in, sort it through, spread it around to dry. —Sandra Dodd