You say WHAT?
Autosomal DNA (atDNA) is the test provided by 23andMe, AncestryDNA, and the one called Family Finder at Family Tree DNA. Although we share 50% of our mother's DNA and 50% of our father's DNA, atDNA randomly combines with every person so one person does not inherit the same DNA segments as their their siblings, and we do not get equal amounts of DNA from our grandparents, etc.
We inherit 22 PAIRS of chromosomes (one chromosome of each pair comes from each parent) and a set of sex chromosomes. Males get a Y-chromosome from dad and an X-chromosome from mom. Females get an X from dad and an X from mom.
Only 23andMe and Family Tree DNA (FTDNA) provide a Chromosome Browser so we can see the segments we share with our matches. 23andMe does have a method of triangulating to determine if matches share the same segment with other matches you have.
At AncestryDNA, you must upload your raw data to GEDmatch, a third-party pool. Even then, you are only compared with those from any of the companies who have also uploaded their raw data. That is, you won't see information on the matches at AncestryDNA unless they have also uploaded to GEDmatch.
However, by looking at a Chromosome Browser, you cannot determine if your matches come from your father's side or your mother's side of the family as we get one chromosome from dad and one from mom for each pair of chromosomes.
Until now, DNA testers uploaded their matching segments into a spreadsheet and sorted them by chromosome, start position and end position to determine which matches could share the same segment. At least three people must be matching on the same segment. However, this method required an email to the group of three or more to see if all of them matched each other on the same segment (give or take a bit) on the same chromosome. Those who matched each other on the same segment have a common ancestor and, therefore, share a common ancestor either your mom or dad's side. If someone doesn't match all in the group, that person shares a common ancestor on the other parent's side. This is called determining Half-Identical Regions. (A Full-Identical Region would be those segments shared by identical twins and there could be some segments which are shared by siblings which match both parents.)
Göran Runfeldt of Sweden has developed a triangulation process using Family Tree DNA. It has been dubbed The Triangulator. Remember, this is still in Beta and does work best on a PC with Chrome. However, Mac users have been able to use it. See his site for instructions.
Instead of repeating all that others have said, I refer you to the following links which include some blogs on the issue as well as the directions.
Roberta J. Estes' blog: DNAeXplained at https://dna-explained.com/2017/10/21/introducing-the-triangulator/
Göran Runfeld's instructions at https://dnagen.net/
Haplogroup blog at http://haplogroup.org/installing-goran-runfeldts-family-finder-segment-triangulator-chrome-extension/