About 10 minutes · What you'll have at the end: your matches organized into colored family groups — the moment DNAGedcom clicks.
Here's the problem with a raw match list: it's thousands of strangers sorted by a number. The question you actually care about — “which side of my family is this person from?” — isn't answered anywhere on it.
Clustering answers it. The idea is simple: matches who share DNA with each other (that's the ICW data you gathered in Lesson 4) almost always descend from the same ancestral couple. Group them, and your match list reorganizes itself into families.
We'll start with the Collins-Leeds Method (CLM) — the classic clustering approach, and the best first cluster because the output is easy to read.
The result is a colored grid: your matches along both axes, with colored blocks along the diagonal. Each colored block is a cluster — a group of cousins who almost certainly share an ancestral couple with you. A typical kit at this range produces somewhere between a handful and a few dozen clusters. That's your family, sorted by branch, from DNA alone.
Take a minute with it. Find a cluster containing a cousin you recognize — whatever branch that cousin belongs to, that's what the whole cluster is about. You've just identified an entire group of matches in one look. Full tool reference: Collins-Leeds Method; how it compares to the other clustering tools: Autosomal Tools.
In Lesson 6 you'll learn to read these clusters like a genealogist — including how to use the ones full of strangers to break through brick walls.