People appreciate mobile apps that feel as though they were designed expressly for the device. For example, when an app fits well on the device screen and responds to the gestures that people know, it provides much of the experience people are looking for. And, although people might not be aware of human interface design principles, such as direct manipulation or consistency, they can tell when apps follow them and when they don't. Read more – ‘Apple’s 27 Guidelines for Mobile User Experience Design’.
The first thing you need to know about captions and subtitles is that captions and subtitles are different. The second thing you need to know about captions and subtitles is that you can safely ignore the differences unless you're creating your own from scratch. I'm going to use the terms interchangeably throughout this article, which will probably drive you crazy if you happen to know and care about the difference. Read more – ‘Mark Pilgrim – A Gentle Introduction to Video Encoding: Captioning’.