What is the Bitcoin scaling problem?

The Bitcoin scaling problem is the tension between how fast new blocks are created and how long it takes those blocks to reach the rest of the network. Bitcoin produces a new block roughly every 10 minutes, while a block can take up to 40 seconds to propagate to 95% of the network. When the block creation rate is too fast relative to propagation time, miners in different parts of the network simultaneously produce valid blocks that conflict with each other — only one can be kept, and the rest are discarded as orphan blocks. This matters for beginners because orphan blocks represent wasted computational work, and according to the source, wasted work directly compromises the security of the network.