I am a Dowling.
My DNA results do not show me as a Dowling.
My test results show me in a sub-clade with the catchy name of R-FGC28340. But what does this mean?
A sub-clade is a sub-group of a clade, which is itself a sub-group of a haplogroup. These are not references to individuals but groups of individuals who share a particular mutation.
As DNA gets passed down from the earliest organisms, every now and then there is a mutation. Something changes in the code, sometimes to evolve a survival trait and possibly sometimes just at random. Some of these mutations remain with us and some do not - that is what makes my DNA different from someone else's and makes us different as people.
This result is a 'Y'-DNA result so is just the male line (much the same applies to the female line with mt-DNA). Y-DNA does not change much or often over hundreds of years, so we can be sure that certain characteristics that consistently figure in a pattern of DNA mean that people are related.
So, from your test you get a haplogroup, possibly with a clade or sub-clade. What can you do with that?
From that, by looking at the characteristics of the group you can determine a 'from and to date' for when they lived and broadly where they were in the world at their period. It won't resolve any major world crisis but I find it interesting to know!
You will also get a list of other people who took a similar test and who also have the same group's DNA in their results. These are relatives! You may not recognise them as the connection may be thousands or even tens of thousands of years ago but relatives non-the-less. This MAY be helpful in establishing your family tree. Often it is not but, at best, you may link to a test taker who has a full and thorough family tree.
You will also get access to 'tools' to explore the result in more depth. Some of these can be technical and, I hate to be the child pointing out the emperor's new clothes don't amount to much but, I have yet to benefit in practical terms from viewing the them.
A final reality check is also worth understanding: not everyone has taken a test. In fact, only a tiny proportion of people have been tested this way. So, you are matching up with a very small, self-selecting group of testers. The upside of this is many of them are passionate genealogists. We have to start somewhere and the more people who test the better, so if you can afford it, do test.