Definition
Bitcoin’s protocol targets a 10-minute average block time through the difficulty adjustment mechanism. However, individual block intervals follow a Poisson distribution, meaning any single block might take anywhere from seconds to over an hour to find.
The 10-minute target is a tradeoff between fast confirmations and network stability. Shorter block times would increase orphan block rates and reduce security. The difficulty adjustment ensures this average holds regardless of total network hashrate.
In Simple Terms
The average time between blocks, targeted at 10 minutes. Individual blocks vary randomly around this average.
The average time between Bitcoin blocks, targeted at 10 minutes. Actual block times vary due to the random nature of mining.