AmigaOS is formed from two parts, namely, a firmware component called Kickstart and a software portion usually referred to as Workbench.

The function of Kickstart is comparable to the BIOS plus the main operating system kernel in IBM PC compatibles.

However, Kickstart provides more functionality available at boot time than would typically be expected on PC, for example, the full windowing environment.

Later versions of the Kickstart contained drivers for IDE and SCSI controllers, PC card ports and other built-in hardware.

Upon start-up or reset the Kickstart performs a number of diagnostic and system checks and then initializes the Amiga chipset and some core OS components.

Normally this code passes control back to the OS (invoking AmigaDOS and the GUI) and using the disk as the system boot volume.

Some games and demos on floppy disk used custom bootblocks, which allowed them to take over the boot sequence and manage the Amiga's hardware without AmigaOS.

Its interfaces offer facilities such as command redirection, piping, scripting with structured programming primitives, and a system of global and local variables.

Stefan Stuntz created a popular third-party widget library, based on BOOPSI, called Magic User Interface, or MUI.

As this API could be bypassed, some developers chose to avoid OS functionality for rendering and directly program the underlying hardware for gains in efficiency.

[12] With AmigaOS 3.5, some RTG systems were bundled with the OS, allowing the use of common hardware cards other than the native Amiga chipsets.

Later, graphics card manufacturers and third-party developers provided their own standards, which included MiniGL, Warp3D, StormMesa (agl.library) and CyberGL.

The Amiga was launched at a time when there was little support for 3D graphics libraries to enhance desktop GUIs and computer rendering capabilities.

Then Amiga boasted many influential applications in 3D software, such as Imagine, maxon's Cinema 4D, Realsoft 3D, VistaPro, Aladdin 4D and NewTek's Lightwave (used to render movies and television shows like Babylon 5).

The Amiga supported a vast number of third-party interfaces for video capture from American and European manufacturers.

There were internal and external hardware solutions, called frame-grabbers, for capturing individual or sequences of video frames, including: Newtronic Videon, Newtek DigiView,[13] Graffiti external 24-bit framebuffer, the Digilab, the Videocruncher, Firecracker 24, Vidi Amiga 12, Vidi Amiga 24-bit and 24RT (Real Time), Newtek Video Toaster, GVP Impact Vision IV24, MacroSystem VLab Motion and VLab PAR, DPS PAR (Personal Animation Recorder), VHI (Video Hardware Interface) by IOSPIRIT GmbH, DVE-10, etc.

Modern PCI bus TV expansion cards and their capture interfaces are supported through tv.library by Elbox Computer and tvcard.library by Guido Mersmann.

Following modern trends in evolution of graphical interfaces, AmigaOS 4.1 uses the 3D hardware-accelerated Porter-Duff image composition engine.

A utility called Say was included with the OS, which allowed text-to-speech synthesis with some control of voice and speech parameters.

[17] Despite the American English limitation of the narrator.device's phonemes, Francesco Devitt developed an unofficial version with multilingual speech synthesis.

Later, the ASDG RRD was added to the Fred Fish series of freeware, shareware, and public domain software (disks 58[21] and 241[22]).

The higher-level part of device and resource management is controlled by handlers, which are not libraries, but tasks, and communicate by passing messages.

The place an assign points to can be changed at any time by the user (this behavior is similar to, but nevertheless distinct from, the subst command in MS-DOS, for example).

For example, the so-called gauge-meter showing the free space on a file system, was replaced with a display in percentage from AmigaOS 2.0 onwards, before being restored in 3.5.

AmigaOS 2.0 rectified the problem of applications hooking directly into the input-events stream to capture keyboard and mouse movements, sometimes locking up the whole system.

AmigaOS 2.1 introduced AmigaGuide, a simple text-only hypertext markup scheme and browser, for providing online help inside applications.

The established AmigaGuide hypertext system gained more usability by using document links pointing to media files, for example pictures or sounds, all recognized by the datatypes.

Yet, according to Hyperion Entertainment, AmigaOS v3.1.4, which was "originally intended as a bug-fix release, it also modernizes many system components previously upgraded in OS 3.9".

[32] In 2020 Hyperion Entertainment released the complete change-notes for v3.1.4, including the changes already made prior on its minor bug-fixing update 3.1.4.1 as a free download, and released its "Locale Extras 45.315", which "includes localization materials for greek, polish and russian languages that require additional system setup to work.

The operating system retains several AmigaOS-like features, including DOS Drivers, mount lists, a TRIPOS based CLI and screen dragging.