In the Ethereum network, every time a transaction or smart contract is executed, it requires computational power to be carried out. This computational power is provided by the nodes on the network, which are incentivized to participate by receiving a small fee for every operation they process, known as a gas fee.

The purpose of the gas fee is to ensure that the network remains decentralized, by providing an economic incentive for people to run nodes and secure the network. Without this mechanism, it would be much more difficult to keep the network running, as there would be no way to compensate the nodes for the computational power they are providing. The gas fee also serves as a way to prevent spam and abuse on the network, by making it more expensive to perform many small operations, as opposed to a fewer larger ones.

Gas fees are paid in Ether, which is the native cryptocurrency of the Ethereum network. The cost of gas is determined by the market forces of supply and demand, with prices rising when more people are using the network and falling when usage is low. Users can check the current gas price on Ethereum network and adjust their own fees accordingly. Gas fees are an important part of the Ethereum ecosystem, as they help to keep the network secure and running smoothly.

Each operation that is performed on the Ethereum virtual machine, has a specific opcode that corresponds to it. These opcodes are the instructions that the EVM uses to execute transactions and smart contracts. Each opcode requires a certain amount of computational power to execute, which is measured in units of gas.

When a user initiates a transaction or smart contract, they must specify the amount of gas they are willing to pay for the operation to be carried out. This gas is then used up as the EVM executes the corresponding opcodes. The more complex the operation, the more gas it will require, and thus the higher the gas fee will be.

As a simple example, let’s say you want to transfer 1 Ether from one account to another. The opcode used for this operation is “CALL”, this operation takes less computational power than a complex contract deployment, so it would require less gas. On the other hand, if you want to deploy a new smart contract, it would require more computational power and thus more gas because it includes more EVM opcodes to be executed

So, gas fee and opcodes are connected because each opcode requires a certain amount of gas to execute, and users must pay for that gas in Ether in order for the EVM to process their transaction or smart contract.

Op codes are also known as operation codes and represent the basic instructions that the EVM can execute as part of a transaction on the Ethereum network.

The EVM is a decentralized virtual machine that processes the opcodes of smart contracts, executing them one by one in the order that they appear in the contract’s code. The EVM is responsible for executing the logic of smart contracts and ensuring that they function as intended.

The set of opcodes available in Ethereum is fixed and limited. New opcodes cannot be added to the EVM, and the existing opcodes are carefully chosen to ensure the security and stability of the Ethereum network. Each opcode corresponds to a specific action that the EVM can take, such as reading data from the blockchain, storing data on the blockchain, or sending a message to another contract.

The cost of a transaction on the Ethereum network is determined by the number and complexity of the opcodes that are required to execute the transaction. When a contract is executed, the EVM processes the opcodes and assigns a cost to each one. The total cost of the transaction is the sum of the costs of all of the opcodes that were executed.

The cost of an opcode is measured in units of gas, and the amount of gas that is required for a particular opcode depends on the complexity of the action that it represents.

The cost of a transaction is important because it determines how much the transaction will cost the user in terms of the cryptocurrency Ether. When a user submits a transaction to the Ethereum network, they must specify the maximum amount of gas that they are willing to pay for the transaction. If the transaction requires more gas than the user has specified, the transaction will fail.

In order to ensure that the Ethereum network remains secure and stable, the cost of opcodes is carefully balanced. If the cost of certain opcodes is too low, they might be abused by malicious actors in order to perform actions that are not intended by the designers of the Ethereum network. On the other hand, if the cost of certain opcodes is too high, it might discourage legitimate users from using them, which could limit the capabilities of the Ethereum network.

In summary, op codes are the basic instructions that the Ethereum Virtual Machine can execute as part of a transaction. The set of opcodes available in Ethereum is fixed and limited, and each opcode corresponds to a specific action that the EVM can take. The cost of a transaction on the Ethereum network is determined by the number and complexity of the opcodes that are required to execute the transaction, and the cost of each opcode is measured in units of gas. The cost of opcodes is carefully balanced in order to ensure the security and stability of the Ethereum network.

https://medium.com/coinmonks/how-gas-and-opcodes-work-in-ethereum-2b93b4f2edc4