Apps, a.k.a. site-specfic browsers (SSB), let you launch your favorite web services quickly in self-contained, distraction-free windows.
Let's forget about switching between annoying browser tabs! Unlike websites, desktop apps include many features to enhance your workflow: you can set your favorite webmail app as default email client, switch between multiple accounts, and protect your data from sneaky eyes with passwords or Touch ID.
Spaces let you manage and organize multiple web services & accounts in a single place and switch between them easily.
Why? Because not all of us want to fill our computers with all kinds of apps. With spaces, you can keep all your messaging apps or Google apps together. Or you can keep all your work apps in one place and personal apps in another, and celebrate work-life balance.