Bitmain releases the Antminer S9 — the first 16nm ASIC miner, delivering 14 TH/s. It became the most iconic and longest-lived Bitcoin miner ever built, securing the network through the 2017 bull run, the 2018 bear market, and well into 2020.
The S9's efficiency was so far ahead of its time that it remained profitable for nearly five years — an eternity in mining hardware. At its peak, S9s represented the majority of Bitcoin's global hashrate. Even after retirement from large farms, S9s found second lives heating homes and greenhouses.
Wikipedia: Bitmain