Ethereum (ETH) is used in various ways, primarily as a digital currency and as a fuel for the Ethereum network. Here are some key uses:

1. Digital Currency: Ether can be used as a peer-to-peer digital currency for financial transactions, similar to Bitcoin. It can be used to buy and sell goods and services at participating merchants and retailers.

2. Transaction Fees: Ether is used to pay transaction fees on the Ethereum network. These fees cover the costs of running the network, including electricity and hardware for nodes, and act as an incentive for people to contribute their computer systems as nodes.

3. Smart Contracts: Ether is used to execute smart contracts, which are self-executing agreements that automate specific actions when conditions are met. These contracts are used in various applications, including decentralized finance (DeFi), gaming, and governance.

4. Decentralized Applications (dApps): Ether is used to power dApps, which are applications that run on the Ethereum blockchain. These applications can store and transfer personal data or manage complex financial transactions.

5. Investment: Ether can be traded and held as an investment, similar to other cryptocurrencies. Its market value can be checked on cryptocurrency exchanges and financial platforms.

6. Collateral: Ether is used as collateral by network validators to secure the Ethereum network.

Overall, Ether plays a crucial role in facilitating transactions, executing smart contracts, and powering decentralized applications on the Ethereum network.

To store Ethereum (ETH) tokens securely, consider the following methods:

1. Hardware Wallets: Use a hardware wallet like Trezor or Ledger to store your ETH tokens. These wallets are offline, password or PIN protected, and require physical access to access the funds. Ensure you buy directly from the manufacturer to avoid potential tampering.

2. Paper Wallets: Create a paper wallet by printing your private keys on paper. This method is accessible but may be fragile and susceptible to physical damage.

3. Browser Extensions: Utilize browser extensions like MetaMask to store ETH tokens. These extensions store private keys encrypted on your browser and require a password for access.

4. Cold Storage: Use cold storage options like Ledger Nano, which can be integrated with Web3 wallets, providing secure storage and access to a variety of Web3 applications.

5. External Owned Accounts (EOAs): Store ETH using an EOA, which is a pair of public and private keys. This method is basic and requires no fees to create.

6. Multi-Chain Wallets: Use multi-chain wallets that support ETH, allowing you to send and receive tokens securely.

7. Web3 Wallets: Utilize Web3 wallets like Wigwam, which provide secure storage and direct access to decentralized applications (dApps).

Remember to always prioritize security by using strong passwords, keeping your private keys safe, and avoiding untrusted sources.

To buy Ethereum (ETH) tokens, follow these steps:

1. Choose a Reputable Trading Platform: Select a trusted and regulated exchange, such as Coinbase, Kraken, or Binance, that offers Ethereum trading. Consider factors like security measures, jurisdictional restrictions, and reputation when making your choice.

2. Create an Account and Verify Your Identity: Sign up for an account on the chosen exchange and provide the required personal information and identification documents. This process may take a few hours to a few days, depending on the exchange.

3. Deposit Currency: Fund your account using a preferred method, such as bank transfers, debit cards, or wire transfers. Be aware of any associated fees and potential cash advance implications if using credit cards.

4. Make Your Ethereum Purchase: Navigate to the exchange's buying interface, enter the amount you want to purchase, and select Ethereum (ETH) as the asset. Confirm your purchase and ensure you understand any fees involved.

5. Withdraw and Store Your Ethereum: For enhanced security, transfer your Ethereum to a cold wallet, which is an offline device that keeps your private keys away from the internet. This minimizes the risk of theft or loss.

Remember to consider the risks involved with cryptocurrency investments and ensure you understand the fees and processes associated with your chosen exchange.