What is it?
Distributed Transaction Coordinator - msdtc.exe

What does msdtc.exe do?
The best straight up explanation of this was found on THIS page. A quote from part of it:

MSDTC is an acronym for Microsoft Distributed Transaction Coordinator. As the name says, MSDTC is a Windows service providing transaction infrastructure for distributed systems. In this case, a transaction means a general way of structuring the interactions between autonomous agents in a distributed system. Each transaction is a state transformation with four key properties - the ACID properties: Atomic (all or nothing), Consistent (legal), Isolated (independent of concurrent transactions) and Durable (once it happens, it cannot be abrogated).
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Virus Precaution:
The msdtc.exe which is from Microsoft is located at c:windowsSystem32msdtc.exe. We've been unable to find any threats that run as msdtc.exe to trick you.