Aperture is a photo editing and management software program that was developed by Apple for the OS X operating system, first released in 2005, and currently available in its App Store. The software handles a number of tasks common in post-production work such as importing and organizing image files, applying corrective adjustments, displaying slideshows, and printing photographs.

Features of Aperture include non-destructive editing, organization of photographs by keyword, faces (using face detection and recognition), and places (using GPS metadata embedded in image files), brushes for applying effects (such as dodge and burn, skin smoothing, and polarization), and exporting to several popular websites, including Flickr, Facebook, SmugMug, and Apple's MobileMe service.

Aperture 3, the latest version of the software, was released on February 9, 2010 and runs on Intel-based Mac computers. On January 6, 2011, Apple announced its availability on the Mac App Store.

Aperture 2.0 was released on February 12, 2008 with a reduced US price of $199. This can be compared with the $499 price tag of version 1.0.

In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture is wide, then uncollimated rays are admitted, resulting in a sharp focus only for rays with a certain focal length. This means that a wide aperture results in an image that is sharp around what the lens is focusing on and blurred otherwise. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane (the narrower the aperture, the darker the image for a given exposure time).

An optical system typically has many openings, or structures that limit the ray bundles (ray bundles are also known as pencils of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that determines the ray cone angle, or equivalently the brightness, at an image point.

Computer software, or just software, is a collection of computer programs and related data that provides the instructions for telling a computer what to do and how to do it. Software refers to one or more computer programs and data held in the storage of the computer for some purposes. In other words, software is a set of programs, procedures, algorithms and its documentation concerned with the operation of a data processing system. Program software performs the function of the program it implements, either by directly providing instructions to the computer hardware or by serving as input to another piece of software. The term was coined to contrast to the old term hardware (meaning physical devices). In contrast to hardware, software "cannot be touched". Software is also sometimes used in a more narrow sense, meaning application software only. Sometimes the term includes data that has not traditionally been associated with computers, such as film, tapes, and records.