It is the successor to the Galaxy S III, which maintains a similar design, but with upgraded hardware, more sensors, and an increased focus on software features that take advantage of its hardware capabilities—such as the ability to detect when a finger is hovered over the screen, and expanded eye tracking functionality, it was released the previous year.

[9][10] A hardware variant of the S4 became the first smartphone to support the emerging LTE Advanced mobile network standard (model number GT-i9506).

[15] In total, more than 80 million Galaxy S4 units have been sold, making it the most selling Android-powered mobile phone of all time.

At the bottom of the device is a microphone and a micro USB port for data connections and charging; it also supports USB-OTG and MHL 2.0.

Near the top of the device are a front-facing camera, an infrared transmitter for usage as universal remote control,[17] proximity, and ambient light sensors, and a notification LED.

[19][20][21][22] In late January 2014, Samsung's Russian website briefly listed a new black model with a plastic leather backing, similar to the Galaxy Note 3.

[18] Unlike previous models, the S4 does not contain FM radio support, citing the increased use of online media outlets for content consumption on mobile devices.

Unlike the predecessor, the S4 is also equipped with a hall sensor for the S View cover, a self-capacitive[29] touch screen layer for Air View and thermometer and hygrometer sensors,[30][6] the last two of which only the Galaxy S4 and Galaxy Note 3 out of all historical Samsung flagship devices are equipped with.

The S4 version for North America, most of Europe, parts of Asia, and other countries contains Qualcomm's Snapdragon 600 system-on-chip, containing a quad-core 1.9 GHz Krait 300 CPU and an Adreno 320 GPU.

On 24 June 2013, a variant supporting LTE Advanced (model number GT-i9506), the first commercially available device to do so, was announced for South Korea.

[40] It also was equipped with increased processing power by using the same CPU (Snapdragon 800) and GPU (Adreno 330) hardware as the Galaxy Note 3 SM-N9005,[39] although no precluded video recording capabilities beyond 1080p at 30 fps.

Head tracking features have been extended on the S4; the new "Smart Scroll" feature can be used to scroll while looking at the screen by slightly tilting head or phone forward or backward,[43] and "Smart Pause" allows the video player to pause videos if the user is not looking at the screen.

"Air View" and "Air Gestures" implement gestures and other functionality (such as previewing images or messages) by holding or swiping a hand or finger slightly above the screen, similarly to Samsung's Galaxy Note series, and adds a feature known as "Quick Glance", which uses the proximity sensor to wake the phone so it can display notifications.

The S4 also introduces Knox in the Android 4.3 update, a suite of features which implements a sandbox for enterprise environments that can co-exist with a user's "personal" data.

[47] In February 2014, Samsung began rolling out an update to Android 4.4.2 "KitKat" for the S4; the update adds user interface tweaks such as a camera shortcut on the corner of the lock screen, options for setting default launcher and text messaging applications, support for printing, and a new location settings menu for tracking and controlling the use of location tracking by apps.

[53][54] US (starting with AT&T and Sprint) and Canadian Samsung Galaxy S4 models received Android 5.0.1 Lollipop update in April 2015.

Additionally, the Galaxy S4 is equipped with an "easy mode" that hides many features and increases the size of on-screen elements for easier readability for novice mobile phone users.

It received praise for its "stunning screen", "superfast processor", and "Great camera", but was criticized for user interface issues.

[92] ReadWrite's Rowinski described the phone as a "solid" and "first-rate smartphone", but criticised Samsung's use of "bloatware, pre-loaded apps and features that you will likely never use".

He criticized the software as "especially weak" and "often gimmicky, duplicative of standard Android apps, or, in some cases, only intermittently functional."

"[95] Consumer Reports named the S4 as the top smartphone as of May 2013 due to its screen quality, multitasking support, and built-in IR blaster.

"[117] In the UK, companies which sold the S4 have varied in their reactions to claims by worried customers for replacement batteries under the Sale of Goods Act.

O2 however insist that the complete phone, with the faulty battery, be returned to them so that they in turn can send it to Samsung to consider the claim.