Based on Y-DNA results and wherever a match exists - project members are divided into distinct lineages, the main aim is to "group" otherwise unknown researchers (Y-DNA matches), i.e., people with a common male progenitor in the
surname-era

Testers are also encouraged to share details of their earliest known patrilineal ancestor.

Unmatched members are grouped by way of their major haplogroup (no meaningful family relationship implied), in the hope that these individuals will eventually pair with a new member, to create a new family group - WARNING - a large dollop of patience is sometimes required for this step