The iPhone is the leading best smartphone model. The first iPhone was introduced in 2007 under the operating system iOS, with a height of 4.5inches and a width of 2.4 inches. It came with a stereo set, USB cable, and a cleaning cloth. It has internal storage of 8GB and external storage of 16GB. It had a resolution of 480 by 320 pixels, and it supported multiple languages and characters. It supported Wi-Fi and Bluetooth. It had a camera of 2.0 megapixels. The windows required the user to install iTunes 7.5 and above. It had a 30 pin connector, a 3.5mm headset minijack, and a dock connector. The iPhone had a built-in rechargeable battery, talk time of up to eight hours, and internet use of six hours.

The reason why it became a significant hit when it was first released is that it embraced diverse user requirements. It had better storage, a camera, and the right color.

iPhone 3G was then released. The 8GB model was black, and the 16 GB was Black or white. It had a GPS, headsets with a mic, power adapter, and a SIM eject tool. The camera was slightly better than the previous model as it offered photo geotagging. It supported mail attachment with different viewable documents, an in-built speaker, microphone; and a sim card tray. It had external buttons like the volume up/down, ring or silent and sensors. It had iTunes 7.7 and a 3G dock. It again became a significant favorite as it made mailing pretty easy. It was portable with appealing colors, and it was user-friendly.

The next iPhone 4 and 4s had the front and rear parts made of glass a steel band around the edges. They have a digital compass, Wi-Fi, and cellular. They allowed free download from iTunes 10.1 and an iTunes store account, and they also allowed internet access. A 16GB internal storage and 32GB external storage was also implemented. The screen resolution is 960 by 640 pixels with a maximum brightness of 500cd. The phone has a camera of 5megapixels, HD video recording of 30 frames per second. They have a LED flash and photo and video geotagging.

If you decide to buy an old model of the iPhone model, you should very much consider your requirements as a user. When you buy an old model it get better over time.

The iPhone 6 plus came with even better features. It comes in silver, gold and space gray. It has a capacity of 16GB, 64GB, and 128GB, which is pretty awesome. It has a height of 6.2inches and a width of 3.06inches. The phone has a screen resolution of 1920 by 1080 pixels. It’s camera is 8 Megapixels with true tone flash, exposure control, burst mode, and the timer mode. It has a fingerprint identification sensor on the home button. iPhone 6 plus has Siri that allows you to use your voice to execute commands on your phone, use it hands-free, listen, and identify songs. It takes a NANO- SIM and is not compatible with the existing micro-SIM cards.

iPhone 7 is a significant hit in the market. It comes in black, jet black, gold, silver and rose gold. The phone has a storage capacity of up to 256GB. iPhone 7 plus has a height of 6.23 inches and a width of 3.07 inches. It has a ten fusion chip. It has a dual camera of 12 megapixels, a 2x optical zoom, auto image stabilization. iPhone 7 Plus also has a fingerprint sensor. It allows FaceTime videos and audio over Wi-Fi or cellular. It also supports Siri, which is activated by only your voice. The power of iPhone 7 plus lasts longer than that of iPhone 6 plus. It uses iOS 12, and it has a straightforward interface to help people with disabilities. It also uses the NANO- SIM.