What is the ⌥ key?

Is this key the same as shift?

If so, why don't people just call it shift? I spent a long time looking around for what this key means. Google returned no results. My MacBook Air keyboard does not have this symbol either.

That is the Option key ( Alt on Windows).

It's not the same as Shift - it's generally used as a secondary modifier for keyboard shortcuts (Command ⌘ being the primary modifier) and for shortcuts that don't perform an action (e.g. Option-8 is a bullet point • and Option-Shift-8 is a degree symbol °).

From the official "macOS User Guide":

• What are those symbols shown in menus on Mac?
• Mac keyboard shortcuts

The first symbol is the option key, located between the command and control keys on a typical Mac keyboard.