Glossary
What is an altcoin?
In one sentence
Altcoin means any cryptocurrency other than Bitcoin — from major established networks to tokens created in an afternoon.
The word is a leftover from the early days, when Bitcoin was the market and everything else was an alternative to it. It survives as a catch-all, which is why it is not very informative on its own: Ethereum and a token launched yesterday are both technically altcoins.
What matters is the assessment, not the label. Useful questions: does the project have a working product or only a roadmap? Who holds the supply, and how much can insiders sell? Does the token actually accrue value if the project succeeds, or is it decorative? Is there activity on the chain, or only on social media?
Applied honestly, that checklist eliminates a great many coins very quickly. Altcoins as a group are considerably more volatile than Bitcoin, far less liquid, and a large proportion of those launched in any given year are effectively worthless within two.
For example
A coin being listed on an exchange is not an endorsement — listing standards vary enormously.