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Introduction to Bitcoin Script: Understanding the Language Behind Bitcoin Transactions

The Bitcoin protocol uses a programming language called Bitcoin Script to specify the guidelines for spending Bitcoin. A straightforward, stack-based programming language is used to create transactions for the Bitcoin blockchain.

We’ll give you an introduction to Bitcoin Script and a rundown of its functionality in this tutorial.

Understanding Bitcoin Script

The requirements that must be satisfied for a Bitcoin transaction to be valid are laid out in the language known as Bitcoin Script. It is a low-level language that works with a data stack.

Each Bitcoin transaction has a script that specifies the circumstances in which it can be spent. The transaction’s output contains this script, also called a “scriptPubKey.”.

Users who want to remove Bitcoins from an output must supply a script that meets the requirements listed in the scriptPubKey. The input for the transaction contains this script, which is referred to as a “scriptSig.”.

A “scriptPubKey + scriptSig” or “scriptPubKey/scriptSig” pair is what the scriptPubKey and scriptSig together are called. The transaction is deemed valid, and the Bitcoins can be spent if the scriptSig meets the requirements outlined in the scriptPubKey.

Basic Operations in Bitcoin Script

The language used by Bitcoin is very basic and works with a stack of data values. A few of the fundamental operations that can be carried out in Bitcoin Script are listed below:

  • Data is pushed onto the stack using the OP_PUSHDATA operation. A hash value, a string, or a number can all be used as the data.
  • The top item on the stack is duplicated by the operation OP_DUP.
  • OP_EQUALVERIFY: If the top two items on the stack are not equal, this operation compares them and returns an error.
  • OP_CHECKSIG: This procedure checks the validity of a digital signature.
  • OP_HASH160: This operation computes the hash value of the top item on the stack using the RIPEMD-160 algorithm.
  • OP_VERIFY: If the top item on the stack is zero, the operation fails and returns an error.

These are only a few of the fundamental operations that are possible with Bitcoin Script. There are currently a lot of other operations that can be used to build more complex scripts.

ScriptPubKey and ScriptSig

As previously mentioned, a scriptPubKey and scriptSig are included in a Bitcoin transaction. Let’s examine these two scripts more closely.

The scriptPubKey, which is part of the transaction’s output and outlines the restrictions on how the bitcoins can be used, is included. It frequently contains a hash of the public key, which is a requirement for the scriptSig to be valid.

The data required to fulfil the scriptPubKey’s conditions are provided by the scriptSig, which is part of the transaction’s input. It frequently contains a digital signature, which is used to confirm that the person using the Bitcoins is the legitimate owner of the private key linked to the public key hash in the scriptPubKey.


The conditions under which Bitcoin transactions can be spent are specified using the straightforward, stack-based programming language known as Bitcoin Script. It serves as a crucial component of the Bitcoin protocol and is used to guarantee the security and legitimacy of Bitcoin transactions.

We gave a brief overview of Bitcoin Script in this tutorial, as well as an explanation of some of the language’s fundamental operations. Therefore, we talked about the scriptPubKey and scriptSig as well as how they function as a pair to guarantee the authenticity of Bitcoin transactions.


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