(Translated by https://www.hiragana.jp/)
Apple - Mission Control - A bird’s-eye view of everything.
The Wayback Machine - https://web.archive.org/web/20110609033616/http://www.apple.com:80/macosx/whats-new/mission-control.html

Mission Control

Mac command central.

Mission Control brings together Exposé, Dashboard, Spaces, and full-screen apps to give you one place to see and navigate everything running on your Mac.

Get there fast.

Get a bird’s-eye view of all the open windows and apps on your Mac. Just swipe up with three fingers on your trackpad or click the Mission Control icon in the Dock, and your desktop zooms out to Mission Control.

Three-finger swipe

Swipe up on the trackpad with three fingers to see every open app and window on your Mac.

See everything. Go anywhere.

In Mission Control, a row of thumbnails across the top of the screen represents Dashboard, desktop spaces, and your full-screen apps. The lower part of the screen shows an Exposé view of the open windows on your desktop grouped by app. To get where you want to go, just swipe left or right. Or click a thumbnail.

Dashboard

Located at the top left for easy access.

Full-screen apps

Appear to the right of your desktop spaces in the top row.

Desktop and windows

Standard-size windows and your desktop appear in the lower part of Mission Control.

Space for all your spaces.

When you need a little more room for your windows and documents, Mission Control lets you create new desktop spaces and quickly navigate among them. You can add and remove spaces with ease. Create a new space by dragging an app to the top row. Moving windows from one space to another is as easy as dragging the window from Exposé to the thumbnail of the space.

Add desktop spaces

Click the + button to the right of the top row to add a new space.