How do you get extra lives in Sonic the Hedgehog?

1. Collecting 100 rings. This is the most common way to get an extra life in Sonic the Hedgehog. When you collect 100 rings, a 1-Up icon will appear. Touching the 1-Up icon will give you an extra life.

2. Defeating a boss. Each time you defeat a boss in Sonic the Hedgehog, you will earn an extra life.

3. Finding a secret life monitor. There are a few secret life monitors hidden throughout the levels in Sonic the Hedgehog. Finding and touching a secret life monitor will give you an extra life.

4. Using a cheat code. There are a few cheat codes that can be used to get extra lives in Sonic the Hedgehog. These cheat codes must be entered on the title screen.