Data structures and encoding
Ethereum creates, stores and transfers large volumes of data. This data must get formatted in standardized and memory-efficient ways to allow anyone to run a node on relatively modest consumer-grade hardware. To achieve this, several specific data structures are used on the Ethereum stack.
You should understand the fundamentals of Ethereum and client software. Familiarity with the networking layer and the Ethereum whitepaper is recommended.
Patricia merkle tries
Patricia Merkle Tries are structures that encode key-value pairs into a deterministic and cryptographically authenticated trie. These are used extensively across Ethereum's execution layer.
Recursive Length Prefix
Recursive Length Prefix (RLP) is a serialization method used extensively across Ethereum's execution layer.
Simple Serialize (SSZ) is the dominant serialization format on Ethereum's consensus layer because of its compatibility with merklelization.