For those of you who don't know, I'm sure you have seen the word recently, not here but on the news. Whether it was about Segwit or something else like that, I think it's important for you to know what they are and how they work. So let's get started.
1. A BIP stands for Bitcoin Improvement Proposal.
BIPs are created when somebody has an idea to improve the Bitcoin network. A BIP is a document with a special kind of format that explains exactly why the proposal is needed and how it will work.
2. BIPs are reviewed by the community
All BIPs are submitted to the mailing list of bitcoin-dev or on Github. That is wheve everyone else involved in Bitcoin can go check out the document and offer their opinions on it.
3. Not all BIPs are accepted
Natrually, some BIPs are rejected, for example if it is too complicated to implement, there is not a need for the BIP, or if it changes the Bitcoin protocol in a way that some people don't like.
A BIP is only accepted into the repository if and after it is agreed on by a majority of people. Around this time, it also gets a number.