1 what is ERC-20 token?
Currently, more than 80% of tokens issued on the Ethereum blockchain are ERC-20 compliant. The ERC-20 protocol was designed on Ethereum platform in November 2015. ERC-20 defines a common list of rules for Ethereum tokens, allowing developers to accurately predict interaction between tokens. The exchange and DApp between them will become relatively convenient.
2 Which address should I use to receive ERC-20 tokens?
ERC20 is an official protocol which can be understood as a standard for tokens that are created on the Ethereum blockchain. Therefore, ETH address can be used to receive ERC-20 tokens.
3 Is miner fee required to transfer ERC-20 tokens?
You have to pay the miner fee in ETH to transfer ERC-20 tokens. In Sallet One Wallet, you can set the miner fee by yourself. Of course, higher miner fee will mean faster transfers.
4 What are Gas, Gas Price and Gas Limit in the Ethereum network？
What is Gas？
Gas is a unit of measuring the computational work （including computation, storage, bandwidth, etc.）of running transactions or smart contracts in the Ethereum network. The gas used for the transaction will be kept by the miners for their work. Transaction can be stored in more than one block and then be broadcast to the Ethereum network. Miners will execute transactions that offers a higher gas price with reasonable gas. If your miner fee is too low for miners to execute the transaction, the blockchain will record the transaction as “Failed”.
What is Gas Price?
Gas price refers to the amount of Ether you’re willing to pay for every unit of gas, and is usually measured in “Gwei”. The higher gas price is, the higher ETH you have to pay for each step of computational work.
One ETH equals to a billion Gwei. 1 Gwei = 0.000000001 ETH. Supposed gas price is 20 Gwei, then it means that the sender is ready to spend 0.00000002 ETH on each unit.
Total cost of a commission for a transaction in ETH:
Tx Fee = Actual Gas Used * Gas Price
For example, if the transaction used 50 units and gas price is 2 Gwei, then the total transaction fee is 50 * 2 = 100 Gwei.
What is Gas Limit?
Gas limit is the maximum amount of Gas that a user is willing to pay for performing this action or confirming a transaction. Since the difficulty varies from transaction to transaction, the exactly gas consumption cannot be determined until the transaction is completed. Therefore, gas limit is the upper limit set by user before the transaction happened.
If the amount for the Gas Limit they indicated is too low, then the transaction is considered invalid and will be dropped, and the Gas spent for calculations will not return to the account. If the gas consumption does not reach gas limit after the transaction is completed, all unused Gas is returned to the sender's account. In other words, the maximum transaction fee is the product of Gas Limit and Gas Price.
5 Why transaction fee is required to transfer ERC20 tokens?
Basically, anyone can read the public chain and anyone can write a new block into the public chain. Writing into the blockchain will consume a certain amount of fee which can be used to power and secure the network. Mining requires a great deal of computing power which translates into a high amount of electricity and power. Miners will charge transaction fee (miner fee) on each transaction.
6 Is the gas fee refunded if the transaction failed?
No. Gas fee is paid for miners to process a transaction. Regardless whether the transaction is successful or failed (insufficient gas limit, wrong contract), the gas fee will be used to process the transaction.
7 Why do I see an ETH transaction with the amount of 0 when sending ERC-20 tokens?
ERC-20 tokens are designed on ETH platform. ERC-20 tokens will rely on ETH platform which will share the same transaction record with ETH.