As you may already know, Family Tree DNA provides an yDNA Haplotree that you can use to not only see where your Kit is located, but also to examine all the other branches that it has reviewed and accepted. You can access this a couple of ways. If you have a Y-DNA Haplogroup badge in the upper right corner of your Dashboard page, simply click on that. Alternatively, you can click on the button (bar) in the Y-DNA section of the Dashboard page that says "Haplotree & SNPs".
Contrary to what some people might assume, there is not one single yDNA Haplotree because there is no overriding authority in this field. Therefore, you might also want to examine those by the International Society of Genetic Genealogy (ISOGG) and YFull:
The ISOGG page also provides answers to a question sometimes asked by testers: Where do the SNP designations come from? If you scroll down that linked page, you will see the list of researchers and laboratories that have discovered various SNPs and the letters they have been assigned. So, for example, M269 means that was the 269th SNP discovered by and named for Dr. Peter Underhill at Stanford University.
The YFull page, like all their products, is very user-friendly, and provides estimates for when SNPs arose.