What is Mining?

How it works

Bitcoin and a handful of other chains use proof-of-work consensus. Miners run specialized hardware (ASICs for Bitcoin) that hashes proposed blocks billions of times per second, looking for a hash output that satisfies the network's difficulty target. The first one to find a valid hash broadcasts the block, gets the block reward (currently 3.125 BTC per block on Bitcoin, halving every ~4 years) plus the transaction fees inside it, and the network moves on to mining the next block.

Difficulty adjusts automatically. As more miners join and total hash rate climbs, the puzzle gets harder, keeping block times around the protocol's target (10 minutes for Bitcoin). When miners drop out, difficulty drops to compensate.

Example

A modern Bitcoin ASIC like the Antminer S21 hashes at ~200 TH/s and pulls about 3.5 kW. At residential US electricity rates of $0.12/kWh, that's $300+ per month in power. Whether mining is profitable depends on:

• BTC price (the 3.125 BTC reward changes value daily)
• Network difficulty (more miners = smaller share of rewards)
• Power cost (industrial mining clusters hunt $0.03–0.05 kWh deals)
• Hardware efficiency (newer ASICs are 2–3× more efficient per joule)

Most home miners stopped being profitable around 2018–2019. Today's Bitcoin mining is dominated by industrial-scale operations near cheap stranded energy: hydro in Quebec and Iceland, flared gas in Texas, geothermal in Iceland.

Why it matters

Mining is the security backbone of Bitcoin. The cumulative hash rate represents the cost an attacker would need to spend to rewrite history — currently in the hundreds of millions of dollars per day. That's what makes "Bitcoin is hard to censor" a real claim and not just a slogan.

Environmental concerns are real and complicated. Bitcoin's energy footprint is comparable to a small country (~150 TWh/year as of 2024). Defenders point to growing renewable share and the practice of monetizing otherwise-wasted energy (flared gas, oversupplied off-peak grid power). Critics point out that even renewable energy spent on mining is energy not going to other uses. There's no resolution to that argument that everyone agrees on.

For everyday users, mining is no longer something to do at home. It's a heavy-industry activity. Buy BTC if you want exposure to Bitcoin; the days of profitable hobby mining are long over.