Early on in bitcoin, a 1MB limit was added to the block size, which puts a cap on the number of transactions that can be included in each block. Now that bitcoi

Early on in bitcoin, a 1MB limit was added to the block size, which puts a cap on the number of transactions that can be included in each block. Now that bitcoin is more popular, there are more transactions then can fit in each block, which means miners will only include the transactions that include the highest fees. There are a number of ways to solve this (the easiest being expanding the block size), but the community is split on the best way forward, so the congestion is getting worse