SigScript and ScriptPubKey are two components of the Bitcoin transaction scripting language.

A SigScript, also known as a signature script, is a piece of data that is included in a transaction and provides proof of ownership of the inputs (previous transactions) used in the transaction. The SigScript typically includes a digital signature, which is generated using the private key of the owner of the inputs. The signature is used to verify that the owner of the inputs has authorized the transaction and to prevent unauthorized use of the inputs.

The ScriptPubKey, on the other hand, is a piece of data that is included in an output of a transaction and specifies the conditions that must be met in order for someone to spend the bitcoins associated with that output. The ScriptPubKey can include one or more conditions, such as a requirement for a digital signature from a specific public key, or a requirement for multiple signatures from multiple public keys.

Together, the SigScript and ScriptPubKey form a complete script that is executed by the network to validate a transaction. The SigScript is used to prove ownership of the inputs, while the ScriptPubKey specifies the conditions that must be met in order to spend the outputs. If the conditions specified in the ScriptPubKey are met, and the signature in the SigScript is valid, the transaction is considered valid and is included in the blockchain.