Certified Bitcoin Professional Practice Exam

Lightweight Bitcoin clients, often referred to as SPV (Simplified Payment Verification) clients, do not maintain a local copy of the entire Bitcoin blockchain. Instead, they operate by downloading only the block headers of the blockchain, which are significantly smaller in size compared to the full blocks that contain all the transactions. This allows them to verify transactions without needing to download and store the entire blockchain, which can be quite large and cumbersome.

By using the block headers, lightweight clients can confirm whether a transaction is included in a specific block, relying on full nodes for the actual transaction data. This design provides the functionality of interacting with the Bitcoin network while conserving storage space and reducing bandwidth usage. Thus, the assertion that lightweight Bitcoin clients do not keep a local copy of the entire blockchain reflects their operational efficiency and purpose.