Recording a slow-motion video on an iPhone is a feature that can be used to capture high-speed actions and present them in a dramatically slowed-down sequence. Slow-motion videos are recorded at a higher frame rate so that when they’re played back at a normal speed, the motion appears much slower than real life. Below are the steps you need to follow to make a slow-motion video using your iPhone:

1. Open the Camera App: Unlock your iPhone and launch the Camera app. You can do this by tapping the Camera icon on your Home screen, Control Center, or Lock screen.

2. Select ‘SLO-MO’ Mode: At the bottom of the screen (or to the side if you’re holding your phone horizontally), you’ll see different camera modes like Photo, Video, Portrait, etc. Swipe through these options until you get to ‘SLO-MO’.

3. Adjust Frame Rate and Quality (Optional): Before recording, you can adjust the frame rate and quality if you have an iPhone that supports these options. Go to Settings -> Camera -> Record Slo-mo to select 1080p at 120 fps or 240 fps depending upon your model.

4. Start Recording: Frame your shot within the camera viewer and press the red record button to start capturing your slow-motion video.

5. Stop Recording: Tap the red button again when you want to stop recording.

6. Edit Video (Optional): To edit the slow-motion effect timing, go to the Photos app and select your video. Tap “Edit” in the top right corner. At the bottom of the editing screen, there is a slider with vertical lines – that’s the frame rate editor. Dragging the wider-spaced lines closer or further from each other adjusts where the slo-mo effect starts and stops in your clip.

7. Save or Share Your Video: After editing, tap “Done” to save your changes. You can then share it using the share sheet icon in Photos with friends through messaging apps, social media platforms, email, or other services available on your iPhone.

Slow-motion videos are great for analyzing sports movements, creating cinematic effects, or just having fun with everyday actions turned into epic sequences. Remember to ensure adequate lighting for best results as slow motion can cause videos to look darker than usual due to faster shutter speed and lesser light coming into each frame.