The iPhone 5s is a smartphone that was developed and marketed by Apple. It is the seventh generation of the iPhone, succeeding the iPhone 5, and was unveiled in September 2013 alongside the iPhone 5c.

The iPhone 5s has almost the same external design as well as the same 4-inch screen as its predecessor, the iPhone 5. The 5s received a new white/gold color scheme in addition to white/silver and space gray/black. The 5s features upgrades mostly in the form of internal hardware; it introduced the Apple A7 64-bit dual-core system-on-chip, the first 64-bit processor to be used on a smartphone, accompanied by the M7 "motion co-processor". A redesigned home button with Touch ID – a fingerprint recognition system which can be used to unlock the phone and authenticate App Store and iTunes Store purchases – was also introduced. The camera was updated with a larger aperture and a dual-LED flash optimized for different color temperatures. EarPods, which were introduced the year prior and had been shipping with the iPhone 5, were included in the box.

The iPhone 5s originally shipped with iOS 7, which introduced a revamped visual appearance among other new features. Designed by Jony Ive, iOS 7 departed from skeuomorphic elements used in previous versions of iOS in favor of a flat, colorful design. Among new software features introduced to the iPhone 5s were AirDrop, an ad-hoc Wi-Fi sharing platform; Control Center, a control panel containing a number of commonly used functions; and iTunes Radio, an internet radio service. The 5s is the first iPhone to be supported through six major versions of iOS, from iOS 7 to iOS 12, and the second iOS device to support five major updates – the first being the iPad 2 which supported iOS versions 4 to 9.

Reception towards the device was positive, with some outlets considering it to be the best smartphone available on the market due to its upgraded hardware, Touch ID, and other changes introduced by iOS 7. Some criticized the iPhone 5s for keeping the design and small display of the iPhone 5, and others expressed security concerns about the Touch ID system. Nine million units of the iPhone 5s and iPhone 5c were sold on the weekend of their release, breaking Apple's sales record for iPhones. The iPhone 5s was the best selling phone on all major U.S. carriers in September 2013.

The iPhone 5s was succeeded as Apple's flagship smartphone by the larger iPhone 6 in September 2014. On March 21, 2016, the iPhone 5s was discontinued following the release of the iPhone SE, which incorporated internal hardware similar to the iPhone 6s while retaining the smaller form factor and design of the 5s.

Before its official unveiling, media speculation primarily centered on reports that the next iPhone would include a fingerprint scanner; including Apple's 2013 acquisition of AuthenTec, a developer of mobile security products, references to a fingerprint sensor on the home button in the beta release of iOS 7 and leaked packaging for an iPhone 5s showing that the traditional home button now had a metallic "ring" around it. Similar ring-based imagery was seen on the official invitation to Apple's iPhone press event in September 2013, where the new device was unveiled. Shortly before its official unveiling, The Wall Street Journal also reported the rumor.

Apple announced the iPhone 5c and the iPhone 5s during a media event at its Cupertino headquarters on September 10, 2013. While the iPhone 5c became available for preorder on September 13, 2013, the iPhone 5s was not available for preorder. Both devices were released on September 20, 2013. While most of the promotion focused on Touch ID, the 64-bit Apple A7 processor was also a highlight during the event.

This is the first-ever 64-bit processor in a phone of any kind. I don't think the other guys are even talking about it yet. Why go through all this? The benefits are huge. The A7 is up to twice as fast as the previous-generation system at CPU tasks, and up to twice as fast at graphics tasks, too.