# High-level Overview of Fraud-proof

**Protocol Spec** pages describe how public blockchains securely scale with fraud-proof technology in general. This page is for those that want to start with looking at a bigger picture of Gazelle's underlying scaling technology.

## Basic Terminologies

**Merkle tree**: a data structure that allows efficient and secure verification of large data, only requiring`log(n)`

of computation where n is the number of leaf nodes in the tree. It is important to highlight that in Plasma, Merkle tree's every leaf node is labled with**a hash of off-chain transactions**offloaded from the mainchain.**Merkle inclusion proof**:**a list of hash**, which proves that a particular off-chain transaction was actually included in a Merkle tree. Aggregator gives a Merkle inclusion proof to L2 clients. L2 clients use**Merkle inclusion proof and corresponding Merkle root**to check whether a transaction has actually been included or not. Data size of Merkle inclusion proof and the computation to check the inclusion are both`log(n)`

where n is the number of leaf nodes in the tree.**Interactive dispute game**: a game played between a claim prover and its opponent. The game is judged by a smart conract using the on-chain data and proofs submitted by Plasma clients.**Dispute period**: period that the dispute game is played. Users have to wait this period to withdraw their assets.