(Translated by https://www.hiragana.jp/)
Apple - App Store - Buy, download, and install apps made for Mac.
The Wayback Machine - https://web.archive.org/web/20110526072258/https://www.apple.com/mac/app-store/

The Mac App Store. More than a thousand apps. One simple new way to get them.

Get the Mac App Store. See How.

With the Mac App Store, getting the apps you want on your Mac has never been easier. No more boxes, no more disks, no more time-consuming installation. Click once to download and install any app on your Mac. The Mac App Store is now available as a software update for any Mac running Mac OS X Snow Leopard.

Great apps for your Mac. Right on your Mac.

The Mac App Store is just like the App Store for iPhone, iPod touch, and iPad. So it’s as easy to find and download Mac apps as it is to add your favorite magazine to iPad or a new game to iPod touch. You can browse Mac apps by category, such as games, productivity, music, and more. Or do a quick search for something specific. Read developer descriptions and user reviews. Flip through screenshots. When you find an app you like, click to buy it.

Install any app with ease.

The Mac App Store revolutionizes the way applications are installed on a computer — it happens in one step. Enter the same iTunes password you use to buy music and apps on your Mac, iPad, iPhone, or iPod touch. Within seconds, your new app flies to your Dock, ready to go. So you can spend more time enjoying new apps and less time installing them.

Keep your apps
up to date.

Since developers are constantly improving their apps, the Mac App Store keeps track of your apps and tells you when an update is available. Update one app at a time or all of them at once, and you’ll always have the latest version of every app you own.

It’s easy to update to the Mac App Store.

Just open the Apple menu in the top-left corner of your screen, choose Software Update, and follow the instructions to download the latest Mac OS X update, which includes the Mac App Store.

The app you need. When you need it.

Can’t open a file you’ve downloaded or received in an email? Mac OS X can search the Mac App Store to find the app that can open the file. Buy what you need instantly and get back to business.

Buy, download, and even
redownload.

You can install apps on every Mac you use and even download them again. This is especially convenient when you buy a new Mac and want to load it with apps you already own.

Calling all creators of amazing apps for Mac.

Find out everything you need to know about developing apps for Mac, from a complete set of development tools to programming guides to sample code. Learn more