The following is a brief list of tools and resources to help genetic genealogy using Y-chromosome DNA. A copy of this list is also in the files section of the Y-DNA – Applied Genealogy & Paternal Origins group on Facebook.
Linkage disequilibrium describes any case in population genetics where the frequency of two alleles being found together implies a non-random association. That is, the odds of both alleles happening together is not random.
Genetic genealogy DNA test kits use saliva samples to collect DNA from dead cells inside our mouths. Test kits from Ancestry.com and 23andMe use spit collection tubes while Living DNA and FamilyTreeDNA use swabs.
An X-match is a genetic match that shares a relevant DNA segment on the X-chromosome. Because the X-chromosome follows a different inheritance pattern than autosomal DNA, X-matches are highly significant for some genealogy applications.