What is Gas?

Whether it is the Ethereum network or other EVM-compatible networks, all operations on the blockchain need to consume Gas, just like a car needs to consume fuel.
Gas Fee = Gas Price * Gas Limit

Gas Price

In the Ethereum Network, Gas Price can be set by the users. The unit for gas price is Gwei, 1 Gwei = 10^9 Wei.
ETH, GWEI, WEI conversion: 1 ETH = 10^9 Gwei = 10^18 Wei
Gas Price is related to the transaction’s package speed. The higher the gas price you are willing to pay, the more incentivizing for miners to package your transaction on priority.

Gas Limit

Gas Limit is the maximum amount of gas a user can consume to conduct a transaction which is usually fixed at 21000 Gas. The Ethereum Yellowpaper pointed out that each transaction needs 21000 Gas, which is why the default gas limit setting in the Gas Fee page is 21000. If you need to change the gas fee, you can go to gas fee - customize - gas.
However, it is recommended that you do not set the gas fee lower than 21000.

How should I Select the Gas Fee when I Initiate a Transaction?

In the gas fee page, O3 offers three gas fee options: "Fast", "Optimal", "Slow". You can select the gas fee option according to your own transfer needs.