How do I add balloons/confetti effects to messages on my iPhone?

The Messages app now includes 4 bubble and 9 screen effects that can enhance any text message sent between iOS devices. These effects include Echo, Spotlight, Balloons, Confetti, Love, Lasers, Fireworks, Shooting Star and Celebration. These animations are available on the "Send with effect" screen" in the Messages app, and they can also be enabled by typing key phrases, such as "Happy Birthday." Here's how to send animated effects in the Messages app:

1. Open your Messages app and select the contact or group you want to message.
2. Type your text message in the iMessage bar as you normally would.
3. Tap and hold down the blue arrow until the "Send with effect" screen appears.
4. Tap Screen.
5. Swipe left until you find the effect you want to use.
6. Tap the blue arrow to send your text message with the selected effect attached.

Remember, anyone who receives your message will need iOS 10.1 or later installed on their device to be able to view the animation.

Update 2: iOS 10.1 allows screen effects to be played with Reduce Motion enabled.

Update: If the balloons/confetti effect option do not appear in your Messages app, it is because you have the Reduce Motion slider enabled. Navigate to Settings -> General -> Accessibility -> Reduce Motion and tap the slider so it is OFF/WHITE.