My own blogposts about DNA.  Effectively, these form a short introductory course.  If you’re an absolute beginner, be sure to read them in this order.

This first post deals with mitochondrial DNA testing and Y chromosomal DNA testing.
Deep ancestral DNA testing

The next five posts deal with how autosomal DNA testing works for genealogy.  They aim to give you enough information to decide whether testing is for you.  (You may prefer to start here, but the first post adds useful contextual information):
Using DNA testing to develop your family research
DNA: unexpected test results
DNA testing: ethical considerations
DNA: Asking other family members to test
DNA for genealogy: where to test

The next three posts will publish in November and December.  They deal with the practicalities of making the autosomal DNA testing work for you.
So your DNA results are in? What now? – coming on 1st November
Thrulines and Theory of Family Relativity – coming on 15th November
Proactive strategies for engaging with your match list – coming on 1st December

The next three posts will deal with chromosome browsers and chromosome mapping.  They will publish in the spring of 2021:
Chromosome browsers and chromosome mapping
DNA Painter


Other very useful links and resources

The Shared centiMorgan Project chart version 4

Shared centiMorgan Project – download PDF outlining latest research, March 2020

The Genetic Genealogy Standards (2015)

International Society of Genetic Genealogy: a non-commercial, non-profit organisation whose mission is to advocate for and educate about the use of genetics as a tool for genealogical research while promoting a supportive network for genetic genealogists.

International Society of Genetic Genealogy glossary of terms used in DNA.  You won’t ever need to look up most of these!  But if you ever do need to understand a term, this is a good place to start.

The Genetic Genealogist – Blaine T Bettinger’s website

The Genetic Genealogist DNA Central – Blaine T Bettinger’s YouTube Channel

DNA explained: Genetic Genealogy: discovering your ancestors, one gene at a time – blog by Roberta Estes, scientist, writer and speaker about genetic genealogy

Your DNA Guide – Diahan Southard’s blog