One of the main improvements of iPhone 4s is Siri, the personal voice recognition assistant. Named the "virtual slave" Siri wants to be a soft voice recognition software. Well, it's more than that. Siri is programmed to recognize words and sentences using an intelligent prediction module. This allows the iPhone 4s to complete simple and advanced task given by voice commands.
For example, you can search the web using certain words, search places near you, definition, you can set an alarm, a note, you can dictate a text message to your friends.
Until recently, Siri was a standalone application but due its success, Apple acquired the company in April 2010. One thing that many forget to mention is that since the time of 3GS, Apple have implemented a voice recognition commands software that (although not perfect) worked. Siri is just the next logical step in voice recognition software for smartphones.
more voice commands: