One of the most common concepts to get your head around is the the difference between gas, gas price, and gas limit. Knowing the difference between these different things is crucial. Let's start with gas.
Gas versus gas limit versus gas price
Gas
Every transaction you do costs gas. What's gas? Well, it's the fuel needed to execute a transaction, denominated in Gwei, which is usually equal to 1*10-9 ETH. Recall the smallest denomination of ETH, wei, which is 1*10-18 ETH, that denominates the amount you will be paying for the transaction.
As we've seen before, you can specify a gas amount in a transaction. We've done this before using web3. Recall that in Chapter 6, Testing Your Dapp, we had the following...
