The following is a short primer in Y-DNA testing and what kind of results you can expect to receive from your test: 

There are two different, but related Y-DNA tests that are useful in genetic genealogy. STR testing is the recommended test for first-time testers. A 37 marker test will provide you with your unique haplotype, and will also give you a predicted haplogroup. Once you have tested, you will be able to join the surname project, and depending on your haplotype, you will be placed with your closest matches in a subgroup. If you have many close matches, you may want to consider upgrading to a 67 or 111 marker test in order to further define your relatedness with your matches.

The other Y-DNA testing method that is available is called SNP testing, either in individual SNPs, SNP packs, or the Big Y-700 test. SNP testing confirms your haplogroup, which is a group of similar haplotypes that share a common ancestor. That common ancestor may have lived many thousands of years ago, and therefore is not really useful for genealogical research. However, with advanced SNP testing, you can discover your terminal haplogroup, (or your most recent common ancestor).

Our ancestors that first carried these unique mutations, or SNPs, lived many thousands of years ago, long before the advent of the written record or surnames. Since we don’t know their names, when they are discovered they are given numerical names like U106 or M222. Each ancestor, or SNP, once discovered, is then added to a huge patrilineal family tree, called the phylogenetic tree. Each SNP represents an ancestor (or group of ancestors since each SNP is roughly calculated to occur over several generations) that lived and died sometime in the past, and their descendants carried their unique SNP mutations down to the present day.

The SNP descendancy is displayed in short-hand on the results page in each subgroup heading. For example, one subgroup contains the following SNP hierarchy:  I-M253 > DF29 >Y2592 > CTS6364 > CTS10028 > S6346 > L22 > Z2338 > CTS6868 > Z74 > FGC9478 > L813 > FGC9487 > FGC9493 > FGC9494 > FGC9486 > Y65994. 

DF29 is estimated to have lived circa 4,600 years ago, or circa 2,581 BC. SNPs Y2592 and CTS6364 are estimated to have lived circa 1981 BC. SNPs CTS10028 and L22 are estimated to have lived circa 1881 BC. SNP L813 is estimated to have lived circa 881 BC. SNP FGC9487 is estimated to have lived circa 481 BC. SNP FGC9494 is estimated to have lived circa 19 AD. SNP Y65994 is estimated to have lived circa 319 AD. 

All of the members in this subgroup are either proven through SNP testing or determined by STR matching to descend from the same common ancestor. Further SNP testing via the Big Y700 test will provide more answers, and more shared SNPs (ancestors) will soon be discovered. Genetic genealogy is still a very new science, and you can be part of the discovery process by participating in Y-DNA SNP testing. Your terminal SNP is your last known shared ancestor with another tester, and will change as more men are tested and more variant SNPs are discovered and named.