BIP: Bitcoin Improvement Proposals.
Purposes: for proposing new features, for collecting community input on an issue, for documenting the design decisions.
BIP-32: Hierarchical Deterministic Wallets.
BIP-39: Mnemonic code for generating deterministic keys.
BIP-42: Soft fork. A finite monetary supply for Bitcoin. (비트코인 반감기)
BIP-44: Multi-Account Hierarchy for Deterministic Wallets.