iOS 10.3 is released see if your iPhone is compatible for the upgrade or NOT
iOS 10 compatible iPhones and iPads list
iPhones:
The iPhone 6s
The iPhone 6s Plus
The iPhone 6
The iPhone 6 Plus
The iPhone SE
The iPhone 5S
The iPhone 5C
The iPhone 5
iPads:
iPad Pro 12.9-inch
iPad Pro 9.7-inch
The iPad Air 2
iPad Air
iPad 4th generation
The iPad Mini 4
The iPad Mini 3
The iPad Mini 2
iPod:
The iPod Touch 6th-generation
iOS 10 NOT compatible iPhones and iPads list
The iPad with Retina Display (3rd Gen) and older 9.7-inch iPads
The iPad Mini
The iPod Touch 5th-generation and older iPod Touch models
The iPhone 4S and older iPhone models