With $4, you can buy cryptocurrencies in small amounts. Here are some options:

Popular cryptocurrencies

1. *Bitcoin (BTC)*: A small fraction of a Bitcoin (unit: Satoshi) can be purchased.

2. *Ethereum (ETH)*: Ethereum is a good option for long-term investment.

3. *Dogecoin (DOGE)*: A popular currency with large trading volumes.

4. *Shiba Inu (SHIB)*: A popular currency with large trading volumes.

Other cryptocurrencies

1. *Cardano (ADA)*: A currency with advanced technology.

2. *Polkadot (DOT)*: A currency with advanced technology.

3. *Solana (SOL)*: A currency with fast trading speed.

Tips

1. Use reliable trading platforms such as Coinbase, Binance or Gemini.

2. Spread the amount across several currencies to improve risk.

3. Use technical analysis tools to improve trading decisions.

4. Do not invest more than your balance.

5. Review the terms and conditions on the trading platform.

Risks

1. Price fluctuations.

2. Security risks.

3. Political risks.

4. Economic risks.

Before you start, review the terms and conditions on the trading platform and log in to your account to start trading.