The equals sign means is equal to. It is telling us that one thing equates to another; that they are the same.
The iPhone 4 is the most recent iPhone to be discontinued from the iOS Update cycle. It did not receive the iOS 8 update, so it's final software version is iOS 7.1.2. You can update to this version through iTunes, or download it from an IPSW repository like this website: https://ipsw.me/.
Apple's iPhone 7 is expected to launch in 2016, bringing a new design and new features.pple just released their 2015 models, the iPhone 6s and the iPhone 6s Plus. Apple has used an alternating S naming formula to mark years where the iPhone does not receive a major redesign since the debut of the iPhone 3GS in 2009.