BIP 33 explained

Bitcoin Improvement Proposal 33 (BIP33), introduced by Pieter Wuille, was designed to solve a problem related to "Stratum," a mining protocol widely used in Bitcoin mining.

Before BIP33 was introduced, when a miner wanted to mine a new block, they had to wait for the mining pool to create a new block template. This was because miners were not able to change the transactions in a block themselves. The Stratum protocol used to simply provide the miner with the block header for mining.

This method was inefficient and had a couple of issues. The primary issue was that it increased the time between when a transaction was broadcast to the network and when it could be included in a block because miners were waiting for a new block template from the pool. This led to longer confirmation times for Bitcoin transactions.

Additionally, it reduced the amount of flexibility that miners had in selecting which transactions to include in a block. Miners generally prefer to include transactions with higher fees as this is more profitable for them. However, without the ability to create their own block template, they were at the mercy of the mining pool to include these higher fee transactions.

BIP33, introducing the "Stratum protocol extensions for pooled mining," proposed a solution to these problems. This extension is often referred to as "getblocktemplate." It allows miners to create their own block templates, giving them the ability to choose which transactions to include in the block.

Using getblocktemplate, the miner can create a block template, including all the transactions they want, and then start hashing the header. This decreases the latency between when transactions are broadcast to the network and when they can be included in a block, effectively reducing transaction confirmation times.

Moreover, it gives miners the autonomy to include transactions with higher fees in their blocks, potentially increasing their profits. This proposal, therefore, brought about a more efficient and flexible mining protocol, contributing to an improved Bitcoin network.