$BTC ETH/BTC pair: You're trading Ethereum against Bitcoin.
If ETH/BTC = 0.07, then 1 ETH = 0.07 BTC.
Why BTC Pairs Matter:
1. BTC as a benchmark: Many traders measure altcoin performance relative to BTC, not fiat.
2. Liquidity: BTC pairs are highly liquid on most exchanges.
3. Market trends: Altcoin/BTC pairs help show if an altcoin is gaining strength relative to Bitcoin.