Glossary
Patricia Merkle Trie
Ethereum's modified, radix-based, hash-keyed Merkle tree — the data structure storing accounts, contract storage, and transaction receipts in every block.
The Merkle Patricia Trie (MPT) combines three ideas: a Patricia trie (radix tree compressing common prefixes), a Merkle tree (each node holds the hash of its children), and Ethereum-specific node types (empty, leaf, extension, branch).
Three MPTs exist per block: the state trie (accounts and balances), the transaction trie (this block's transactions), and the receipts trie (their receipts/logs). The root of each is in the block header. The MPT is being replaced by Verkle trees on the long-term roadmap.