There are two major categories of Ethereum wallet: hot and cold. The hot wallet stores your keys online so you can easily access them from anywhere in the world as long as you have internet access. However, it’s definitely not the best option because your account could be hacked and your funds stolen. Cold wallets, on the other hand, store your keys offline and only go online when you want them to. Naturally, this makes them more secure and lowers the probability of attack.