In plain English
What Altcoin means
Altcoin is shorthand for “alternative coin,” meaning a non-Bitcoin cryptocurrency. It can refer to a native coin of another blockchain, a token on an existing chain, or a project with a very different purpose from Bitcoin.
Why it matters
The term helps separate Bitcoin from the rest of the crypto market, but it can hide major differences among assets. Some altcoins are payment networks, some are smart-contract platforms, and some are speculative tokens with limited utility.
Example
Ether is often called an altcoin because it is not Bitcoin, even though it is the native coin of Ethereum. A governance token for a decentralized app is also commonly lumped into the altcoin bucket, though that classification is broad.
Quick answers
Common questions
Does altcoin mean low quality?+
No. It only means non-Bitcoin. Quality, liquidity, and risk vary widely.
Is Ethereum an altcoin?+
Commonly yes in market usage, because it is not Bitcoin.
Sources