Amazon often runs limited-time promotions offering a couple dozen apps -- games, utilities and more -- absolutely free.
This being Amazon, though, you no doubt need an Amazon product -- Kindle Fire tablet, Fire Phone, etc. -- to take advantage of these offers, right?
Wrong! Android apps are Android apps, and you can access the Amazon Appstore via pretty much any Android-powered device. It just requires a little tweaking. Here's how (on a device running Android 4.4 -- the process is virtually identical in earlier versions):
Step 1: On your phone or tablet, tap Settings > Security. Scroll down to "Unknown sources" and tap the check box to enable this feature. (The "unknown source" in this case is the Amazon Appstore.)
Step 3: Once the download is complete, swipe down from the top of the screen to open your notifications view, then tap the Amazon Appstore entry to start the installation. Agree to the conditions by tapping Next or Install (whichever appears).
And that's it! Now just run the app and browse the Appstore, same as you would Google Play.
Speaking of which, if you want to learn more about this, check out "How to install apps outside of Google Play."