In one sentence, describe what the following article is about:

It's a light-blue app with a white "A" on it. You'll likely see this on the Home Screen. This button, which resembles a magnifying glass, is at the bottom of the screen. You'll see this at the top of the screen. This button is in the bottom-right corner of the screen. WhatsApp resembles a green app with a white speech bubble encompassing a phone. This button is in the same place as GET. If you've recently logged into your Apple ID in the App Store, you won't have to do this. You can also use your Touch ID if your iPhone supports it. It's to the right of WhatsApp. Doing so will open WhatsApp, allowing you to proceed with setting it up. These windows will ask if you want to allow WhatsApp access to your contacts and whether or not WhatsApp can send notifications to you. It's at the bottom of the screen. Your phone number goes in the text field that's in the middle of the screen; Done is in the top-right corner. WhatsApp will send a confirmation code to your iPhone's Messages. It's a green app with a white speech bubble. It will say something like "Your WhatsApp code is [six-digit number]..." in the text's body. As long as you do so correctly, WhatsApp will allow you to finish customizing your profile. Do so by tapping the "Your name" text field in the middle of the screen and typing in your name.  You can also add a profile picture on this page. You may also have the option of tapping Restore in the top-right corner of the screen to restore your chat history. This will only apply if you've used WhatsApp before on this phone. Your iPhone's WhatsApp is now installed and set up, meaning that you're ready to begin using WhatsApp!

Summary:
Open the iPhone's App Store. Tap Search. Tap the "Search" bar. Type whatsapp into the search bar, then tap Search. Tap GET to the right of WhatsApp. Tap INSTALL when prompted. Enter your Apple ID password if asked. Wait for your download to finish, then tap OPEN. Tap OK or Don't Allow for any pop-up windows. Tap Agree & Continue. Type in your phone number, then tap Done. Tap Yes when prompted. Press the Home button, then open Messages. Open the text message from WhatsApp. Type the six-digit code into WhatsApp. Enter your name. Tap Done.