A **BTC pair** refers to a cryptocurrency trading pair where **Bitcoin (BTC)** is one of the two assets being exchanged. It represents the market value of one cryptocurrency *relative to* Bitcoin.
* **How it Works:** In a pair like `ETH/BTC`, you see how much Bitcoin (BTC) is needed to buy one Ethereum (ETH). If `ETH/BTC = 0.05`, it means 1 ETH costs 0.05 BTC.
* **Base & Quote Currency:** BTC is usually the **quote currency** (the benchmark). So, `X/BTC` shows how much BTC one unit of `X` (like ETH, SOL, or LTC) costs.
* **Major Pairs:** Common examples are `ETH/BTC`, `LTC/BTC`, `SOL/BTC`, and stablecoin pairs like `BTC/USDT` or `BTC/USDC` (where BTC is the base currency).
* **Significance:** BTC pairs are fundamental in crypto markets. They allow traders to:
* Altcoin Valuation: Assess altcoin value without involving fiat currencies.
* Portfolio Diversification: Move value between altcoins using BTC as the intermediary.
* Liquidity: Many altcoins have their deepest liquidity against BTC.
* **Key Insight:** Trading BTC pairs involves exposure to *both* the price movement of BTC *and* the paired altcoin. A rising BTC can cause an altcoin's BTC price to fall even if its USD value stays stable.
Essentially, BTC pairs are the core mechanism for valuing and exchanging other cryptocurrencies directly against the original digital asset.