What Happens if Two Miners Find a Block at the Same Time?

Two miners may find a valid block at the same time. In such a situation, we have a race condition. It is depicted in the following figure where there is a block 3 and a block 3’.

What does this Mean for me?

The longer the chain is, the harder it is for an attacker to change it afterward. In Bitcoin, one suggests waiting for six blocks to build upon the block where my transaction is included to be sure it stays in the longest chain. If you are a merchant, you will wait for six blocks until you would give the item to the customer.

With an average block time of 10 minutes, you can expect to wait for approximately one hour. This is not very convenient.

For that reason, developers work on so-called layer 2 technologies that speed up transactions. But for us, this is not important here.