Ancestry DNA in Genealogy Research

Ancestry was founded in 1996 and has been selling DNA tests since 2012. They are based in Lehi, Utah. They sell Ancestry kits for $99 and Ancestry plus traits for $119. Often you can also add a three month membership to Ancestry's record database for $1 when you purchase a kit through them.

Database Size
The biggest advantage to AncestryDNA is their database. As of November 2018, they have sold over 18 million DNA kits. The sheer size of their database makes it more likely that you will find a genetic relative of interest to your problem who has already happened to test by sheer luck.

Thrulines
Ancestry offers the ability to link your DNA and pedigree together. You can upload your tree, link your DNA to yourself in the tree and then Ancestry will start comparing your tree against all your genetic relatives who also have linked their trees to their DNA. Not everyone has done this and many users have both DNA and a tree, but have not linked the two.

After Ancestry has compared your tree and tried to find as many genetic connections as possible, Ancestry will allow you to see all of these possible connections using Thrulines. Thrulines allows you to click on an Ancestor, and then it shows you all the other matches it thinks descends from that Ancestor and their relationships. It can even use their massive database of online trees to fill in some of the gaps when a match of interest only has a partial tree.

One important thing to know about Thrulines is that it does not "go through the DNA." The formulas is simply if two people share DNA, their trees are sought for a common ancestor, but the DNA still needs to be analyzed to make sure that Thrulines found the right common ancestor. For example, Tanner Tolman has a match that according to the paper trail should be related on his grandmother's side. However, there was a non-paternal event and this particular individual is actually genetically related on his grandfather's side. This is obvious when looking at the shared matches, but Thrulines incorrectly assumes the relationship is on grandmother's side. In other words, Thrulines is great, but do not accept it without verifying the conclusions.

Clustering
Ancestry offers the ability to manually sort your matches into up to 24 groups and then assign your DNA matches to those said groups. You can create custom groups, assign each group a color and then place colored dots on each match you believe belongs in that group. You can use these dots with the Leeds method to help identify matches that may be related to your brick wall ancestor. Ancestry used to offer a feature to cluster your matches automatically, but this has been discontinued.

Disadvantages
The biggest disadvantage to Ancestry is their strict privacy rules. They do not have a chromosome browser, they do not have an auto cluster tool, and although they let you see people who share DNA with both you and another genetic match, they do not let you see how closely those shared matches are related to the other person. This can make things difficult when trying to construct a hypothetical tree or when people do not respond to emails asking for more information (which happens frequently). Many people in Ancestry's large database, bought the test, looked at their ethnicity results once, and then never logged in again. Also, to get the full value out of your AncestryDNA test, you will need a membership to Ancestry. Otherwise, you will not be allowed to look at the trees uploaded by your matches.