The term market dominance or market dominance of 55.97% for Bitcoin refers to the fact that Bitcoin holds 55.97% of the total market cap of all cryptocurrencies.
More clarification:
Total market cap of all cryptocurrencies = 100%.
Bitcoin alone holds 55.97% of this value.
The remaining altcoins (such as Ethereum, Ripple, etc.) make up the remaining 100%.
In other words, Bitcoin is still the most dominant and popular currency in the digital market, and it constitutes the largest percentage of the total capital invested in digital currencies.
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Why is this important?
A high control ratio may indicate investor confidence in Bitcoin compared to other currencies.
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Its decline may indicate that liquidity is moving towards altcoins.