Lightning, Atomic Swaps, and Taproot - A Legacy of SegWit
SegWit is a soft fork implemented to make transactions more efficient and to address the issue of transaction malleability. SegWit allows for Lightning and Atomic Swaps and improves Script.
Nakamoto Improvement proposals (NIPs) are suggestions for improving the Nakamoto protocol. They are submitted by developers and other interested parties and then reviewed and debated by the community.