Coin Mixer

Basics

• Aka Tumbler
• "A coin mixer is essentially a means of making cryptocurrency transactions more anonymous and harder to track. People who wish to have higher levels of privacy and anonymity with their Bitcoin and altcoin transactions frequently use coin mixers to accomplish this."

Well Known Mixers

• Mixers come and go through the years but a couple well known as of 1-2020 are: Wasabi and Samourai (for BTC) and Cashfusion (for BCH)
• A 'State of the Mixers' of the Ethereum system can be read here (9-2019).