Maximum coin supply in cryptocurrency terms refers to the total number of coins of a particular cryptocurrency project that will ever exist.
For some projects, this limit is hard-coded into their infrastructure. For example, for Bitcoin, it is set at 21,000,000 BTC.
For Ethereum, there is no fixed limit, however, there is the concept of coin burning [↗], which reduces the number of coins in circulation based on certain rules.
These limits are largely put in place to control inflation.
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