Autosomal STRs provide a much stronger analytical power because of the random matching that occurs between pairs of chromosomes during the zygote-making process.
[2] DYS is a variation on the jargon used in human autosomal STR testing where the second character is typically reserved for the chromosome number (e.g. D8S1179).
These regions, called "variable number short tandem repeats", are what is looked at when performing STR analysis.
The likelihood of two people having the same number of repeated sequences is extremely small, and becomes even smaller the more regions that are analyzed.
If crime scene DNA is ample and all 13 autosomal loci accessible, the likelihood of two unrelated people matching the same sample is around one in one billion.
Forensic databases (without individual information, for frequency purposes): In genetic genealogy, Ysearch used to be the last sponsored database containing publicly submitted surnames and Y-STR haplotypes until its decommission on May 24, 2018, preceding by a day the implementation of the General Data Protection Regulation in the European Union, following a prolonged period of lacking support from its creator, Family Tree DNA.