Shield

A spherical object that protects Sonic.

In Sonic 1 and Sonic 2, you can only get a bog-standard Blue Shield.

In Sonic 3 & Knuckles, you can get a Water Shield, which stops you drowning and lets you do bounces indefinitely. You can also get a Fire Shield, to protect you from flames and let you do sideways attacks in the air. And finally you can get a Lightning Shield, which protects you from electric damage and lets you to a double-jump, as well as attracting rings. Note that the latter two will vanish if you enter water, but if you are super or hyper you will still attract rings underwater.

In the Advance games, you can get a bog-standard Blue Shield which is now, strangely enough, teal colored, or you can get a Magnet Shield which attracts rings. It's a shame they didn't keep the shield moves from S3&K.