The proximity sensor immediately turns off the display when the iPhone is lifted to ear. With this sensor the power is saved and accidental dialing is prevented.

The display is automatically brightens the iPhone by the ambient light sensor when the sunlight or bright rooms and dims in darker places. 

 - Technology, Entertainment and Design(TED): Allows to watch and listen to world’s most fascinating people have to say, all on the iPhone.
 - Market Watch: Breaking news about the investments can be seen. To do so, open the Stocks app and rotate.
 - Trends: Latest runway shows, videos from Vogue’s fashion library, reviews, exclusive party pictures, fashion news updates can be seen on Style.com. 

iPhone responds to motion using a built-in accelerometer.
The accelerometer detects the movement and changes the display accordingly, at the time of rotating iPhone from portrait to landscape. 

It is similar to MacOS X architecture

It acts as an intermediary between the iPhone and iPod hardware an the appearing applications on the screen

The user created applications never interact directly with the appropriate drivers, which protects the user applications from changes to the hardware. 

Video: Videos can be edited, shared. High quality VGA video can be shot in portrait or landscape.

- 3 Megapixel Camera: Still photos with greater quality can be taken

- Voice control: It recognizes the names in contacts and recognizes the music on iPod.

- Compass: iPhone 3GS has built-in digital compass, used to point the way.

- Internet Tethering: Internet surfing can be done from anywhere. A 3G connection can be shared on Iphon3 with Mac notebook or laptop.. 

Android uses many security measures to keep them away from the hackers. They have designed by making changes to the devices or installing a software service on the mobile. Android application uses sandbox that is very popular and allow limited access to the information that is very private and sensitive for the user. It allows the permissions to be set for the use of the information. The security measures that are provided by android is the use of the encryption of the messages that allow user to remain without worry about there phone security. They also consists of user terms and agreements that also taken care of. Most of the time android doesn't allow other applications to run on their system but it can be done by using different resources that are available on-line. As, android is open source it is not fully secure but lots of security issues are being solved for make it more popular and bug free.

The status of an activity can be start and stop only. The start means the activity is up and running. It is in execution state and performing some actions. Whereas the stop state defines that the activity is being stopped and performing no action on the system. To see or check the status of an activity there is a command that has to be used like NEW_TASK_LAUNCH flag that keeps the track of all the activities that are running and the main command under which the flag resides is given as startActivity() call. To bring the activity stack in front of the process that is already running require the command mentioned above to be used. The activity can be started remotely by using the remote services. These services allow easy interaction with the client and provide the sample to show it on the local server.

The android system will keep all the process that are hosting the services together at one place till the time the service is not started or connected to the client. The priority of the process is divided when running low on memory or when the process has to be killed. The process lifecycle is as follows:
- The service is running currently then the methods onCreate(), onStartCommand(), and onDestroy()methods, will run in the foreground to execute the process without being killed.
- The service is already started then the process can be considered as less important then the processes that are currently visible and used. This is done as there are only few processes that are visible to the users on the screen.
- The clients are bounded to the services they are providing requires more priority in the execution list.
- The service that is started uses startForeground(int, Notification)API to allow all the services to run in the foreground state. The system considers only the services where the user is still active as the services not to be killed.