It is the youngest of the five United States service academies, having graduated its first class in 1959. Graduates of the Academy's four-year program receive a Bachelor of Science degree, and most are commissioned as second lieutenants in the Regular United States Air Force.
The SIM tray is located on the right side of the iPhone 4. Like the rest of the iPhones, there is a small hole used to release the SIM tray. A paper clip is the tool of choice. Place the paper clip in the hole a press in firmly. Make sure the paper clip fits in the hole.
The short answer is, it's a Subscriber Identity Module, and it is a small circuit board which is placed in your iPhone (or any GSM phone) in order to identify it to your carrier. It's why you can swap SIMs in GSM phones and your phone number, voice, and data plans are swapped right along with it.On older devices, especially feature phones, it also stored things like text messages and contacts). The SIM card allows you to change cellular phones and keep the same user data. The SIM card is what lets your carrier know that you're the account holder of the iPhone using it.