iPhone 4

The iPhone 4 is a touchscreen smartphone developed by Apple. It is the fourth generation of iPhone, and successor to the iPhone 3GS. It is particularly marketed for video calling, consumption of media such as books and periodicals, movies, music, and games, and for general web and e-mail access. It was announced on June 7, 2010, at the WWDC 2010 held at the Moscone Center, San Francisco,^[6] and was released on June 24, 2010, in the United States, the United Kingdom, France, Germany and Japan.
The iPhone 4 runs Apple's iOS operating system, the same operating system as used on previous iPhones, the iPad, and the iPod Touch. It is primarily controlled by a user's fingertips on the multi-touch display, which is sensitive to fingertip contact.
The most noticeable difference between the iPhone 4 and its predecessors is the new design, which incorporates an uninsulated stainless steel frame that acts as the device's antenna. The internal components of the device are situated between two panels of chemically strengthened aluminosilicate glass.^[7] It has an Apple A4 processor and 512 MB of eDRAM, twice that of its predecessor and four times that of the original iPhone. Its 3.5-inch (89 mm) LED backlit liquid crystal display with a 960×640 pixel resolution is marketed as the "Retina Display".

Apple iPhone 4 (UMTS/GSM model)
Developer	Apple Inc.
Manufacturer	Foxconn (UMTS/GSM model) Pegatron (CDMA model)[1]
Slogan	This changes everything. Again.[2]
Form factor	Capacitive Touchscreen smartphone
Generation	4
Release date	GSM model: 24 June 2010[a] CDMA model: 10 February 2011[a]
Operating system	iOS 4.3.2 (build 8H7) (GSM) Released April 14, 2011; 6 days ago (2011-04-14) iOS 4.2.7 (build 8E303) (CDMA) Released April 14, 2011; 6 days ago (2011-04-14)
Power	Built-in rechargeable Li-ion battery 3.7 V at 1420 mAh[3]
CPU	Apple A4 (ARM Cortex-A8)[4]
GPU	Apple A4 (PowerVR SGX 535)[4]
Storage capacity	16 GB or 32 GB flash memory
Memory	512 MB eDRAM[5]
Display	3.5-inch (89 mm) diagonal 1.5:1 aspect ratio widescreen LED backlit IPS TFT LCD Retina display 640×960 resolution at 326 ppi (0.61 Megapixels) 800:1 contrast ratio (typical) 500 cd/m2 max brightness (typical) Fingerprint-resistant oleophobic coating on front and back glass
Audio	Single loudspeaker 3.5 mm TRRS Frequency response: 20 Hz to 20 kHz
Input	Multi-touch touchscreen display Push-buttons Dual microphone 3-axis gyroscope 3-axis accelerometer Digital compass Proximity sensor Ambient light sensor
Rear camera	5 MP back-side illuminated sensor HD video (720p) at 30 fps 1.75 μm size pixels 5× digital zoom Tap to focus video or still images LED flash Photo and video geotagging
Front camera	0.3 MP (VGA) SD video (480p) at 30 fps 25.17 μm size pixels Tap to focus video or still images Photo and video geotagging
Connectivity	Wi-Fi (802.11 b/g/n) (2.4 GHz only) Bluetooth 2.1 + EDR GSM model: Quad-band GSM/GPRS/EDGE (800 850 900 1800 1900 MHz) Quad-band UMTS/HSDPA/HSUPA (800 850 900 1900 2100 MHz) (800 MHz not yet announced as supported by Apple) CDMA model: Dual-band CDMA/EV-DO Rev. A (800 1900 MHz)
Hearing aid compatibility	GSM 3G 850/1900 MHz M4, T4 2G 850 MHz M3, T3 2G 1900 MHz M2, T3 CDMA M4, T4
Online services	App Store, iTunes Store, iBookstore, MobileMe
Dimensions	115.2 mm (4.54 in) (h) 58.66 mm (2.309 in) (w) 9.3 mm (0.37 in) (d)
Weight	137 g (4.8 oz)
Predecessor	iPhone 3GS
Related articles	iPad, iPod Touch (comparison)
Website	Apple – iPhone

Cloud Computing

Cloud computing refers to the provision of computational resources on demand via a computer network. In the traditional model of computing, both data and software are fully contained on the user's computer; in cloud computing, the user's computer may contain almost no software or data (perhaps a minimal operating system and web browser only), serving as little more than a display terminal for processes occurring on a network of computers far away. A common shorthand for a provider's cloud computing service (or even an aggregation of all existing cloud services) is "The Cloud".
The most common analogy to explain cloud computing is that of public utilities such as electricity, gas, and water. Just as centralized and standardized utilities free individuals from the difficulties of generating electricity or pumping water, cloud computing frees users from certain hardware and software installation and maintenance tasks through the use of simpler hardware that accesses a vast network of computing resources (processors, hard drives, etc.). The sharing of resources reduces the cost to individuals.
The phrase “cloud computing” originated from the cloud symbol that is usually used by flow charts and diagrams to symbolize the internet. The principle behind the cloud is that any computer connected to the internet is connected to the same pool of computing power, applications, and files. Users can store and access personal files such as music, pictures, videos, and bookmarks or play games or use productivity applications on a remote server rather than physically carrying around a storage medium such as a DVD or thumb drive. Almost all users of the internet may be using a form of cloud computing though few realize it. Those who use web-based email such as Gmail or Hotmail instead of receiving mail on their computer with Outlook or Entourage are the most common examples of such users.

Technical description

The National Institute of Standards and Technology (NIST) provides a concise and specific definition:

Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.^[3]

Cloud computing provides computation, software, data access, and storage services that do not require end-user knowledge of the physical location and configuration of the system that delivers the services. Parallels to this concept can be drawn with the electricity grid, where end-users consume power without needing to understand the component devices or infrastructure required to provide the service.
Cloud computing describes a new supplement, consumption, and delivery model for IT services based on Internet protocols, and it typically involves provisioning of dynamically scalable and often virtualized resources^[4][5] It is a byproduct and consequence of the ease-of-access to remote computing sites provided by the Internet.^[6] This frequently takes the form of web-based tools or applications that users can access and use through a web browser as if they were programs installed locally on their own computers.^[7]
Typical cloud computing providers deliver common business applications online that are accessed from another Web service or software like a Web browser, while the software and data are stored on servers.
Most cloud computing infrastructures consist of services delivered through common centers and built-on servers. Clouds often appear as single points of access for consumers' computing needs. Commercial offerings are generally expected to meet quality of service (QoS) requirements of customers, and typically include service level agreements (SLAs).^[8]