To reset an iPhone, follow these steps:

Method 1: Soft Reset (Force Restart)

1. Press and hold the Sleep/Wake button and the Volume Down button simultaneously for at least 10 seconds.
2. Release the buttons when the Apple logo appears.

Method 2: Factory Reset (Erase All Content and Settings)

1. Go to Settings > General > Reset.
2. Tap “Erase All Content and Settings”.
3. Enter your Apple ID password to disable Activation Lock.
4. Tap “Erase Now” to confirm.

Method 3: Reset iPhone via iTunes

1. Connect your iPhone to your computer and open iTunes.
2. Select your iPhone from the top left menu.
3. Click “Summary” > “Restore iPhone”.
4. Click “Restore” to confirm.

Method 4: Reset iPhone via Finder (for macOS Catalina and later)

1. Connect your iPhone to your Mac and open Finder.
2. Select your iPhone from the left sidebar.
3. Click “General” > “Restore iPhone”.
4. Click “Restore” to confirm.

Important:

Before resetting your iPhone, make sure to:
Back up your data to iCloud or iTunes.
Remove your SIM card and any other external accessories.
A factory reset will erase all data, settings, and apps on your iPhone.
If you’re selling or giving away your iPhone, make sure to erase all content and settings and remove the device from your Apple ID account.

Here’s a brief history of the iPhone:

2007: iPhone (1st generation)

Announced by Steve Jobs on January 9, 2007
Released on June 29, 2007
4GB, 8GB, or 16GB storage options
3.5-inch touchscreen display
2MP camera
No App Store (only pre-installed apps)

2008: iPhone 3G

Announced on June 9, 2008
Released on July 11, 2008
Added support for 3G networks
Introduced the App Store
8GB or 16GB storage options

2009: iPhone 3GS

Announced on June 8, 2009
Released on June 19, 2009
Improved camera (3MP) with video recording
Voice Control and Compass app
16GB or 32GB storage options

2010: iPhone 4

Announced on June 7, 2010
Released on June 24, 2010
New design with stainless steel frame and glass front/back
5MP camera with LED flash
FaceTime video calling
16GB or 32GB storage options

2011: iPhone 4S

Announced on October 4, 2011
Released on October 14, 2011
Improved camera (8MP) with Siri virtual assistant
Dual-core A5 processor
16GB, 32GB, or 64GB storage options

2012: iPhone 5

Announced on September 12, 2012
Released on September 21, 2012
Larger 4-inch display
Lightning connector replaces 30-pin dock connector
16GB, 32GB, or 64GB storage options

2013: iPhone 5S and 5C

Announced on September 10, 2013
Released on September 20, 2013
iPhone 5S: Fingerprint recognition (Touch ID), 64-bit A7 processor
iPhone 5C: Colorful plastic casing, lower price point

2014: iPhone 6 and 6 Plus

Announced on September 9, 2014
Released on September 19, 2014
Larger 4.7-inch (6) and 5.5-inch (6 Plus) displays
Apple Pay mobile payments
16GB, 64GB, or 128GB storage options

2015: iPhone 6S and 6S Plus

Announced on September 9, 2015
Released on September 25, 2015
Improved cameras (12MP) with 4K video recording
3D Touch display
16GB, 64GB, or 128GB storage options

2016: iPhone SE, 7, and 7 Plus

Announced on March 21, 2016 (SE) and September 7, 2016 (7 and 7 Plus)
Released on March 31, 2016 (SE) and September 16, 2016 (7 and 7 Plus)
iPhone SE: Compact 4-inch design
iPhone 7 and 7 Plus: Water-resistant, dual cameras (7 Plus), wireless headphones

2017: iPhone 8, 8 Plus, and X

Announced on September 12, 2017
Released on September 22, 2017 (8 and 8 Plus) and November 3, 2017 (X)
iPhone X: Edge-to-edge OLED display, facial recognition (Face ID)
iPhone 8 and 8 Plus: Wireless charging, improved cameras

2018: iPhone XR, XS, and XS Max

Announced on September 12, 2018
Released on September 21, 2018 (XS and XS Max) and October 26, 2018 (XR)
iPhone XR: Budget-friendly option with 6.1-inch LCD display
iPhone XS and XS Max: Improved cameras, faster processors

2019: iPhone 11, 11 Pro, and 11 Pro Max

Announced on September 10, 2019
Released on September 20, 2019
Dual cameras (11) and triple cameras (11 Pro and Pro Max)
Night mode, improved battery life

2020: iPhone 12 series

Announced on October 13, 2020
Released on October 23, 2020 (12 and 12 Pro) and November 13, 2020 (12 mini and 12 Pro Max)
New design