How do I reinstall an application via the Mac App Store?

macOS Mojave and above:
1. Open the Mac App Store
2. Sign in using your Apple ID
3. Click your name in the bottom left corner of the window
4. Locate the app in the list
5. Click the 'Install' button, it looks like a Cloud with an arrow pointing down

Older macOS versions:
1. Open the Mac App Store
2. Sign in using your Apple ID
3. Click the Purchases tab
4. Locate the app in the list
5. Click the 'Install' button