Control Unit

A control unit in general is a central (or sometimes distributed but clearly distinguishable) part of the machinery that controls its operation, provided that a piece of machinery is complex and organized enough to contain any such unit.
Source: http://en.wikipedia.org/wiki/Control_unit

Digital Camera

A digital camera (or digicam) is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. Most 21st century cameras are digital.

Source: http://en.wikipedia.org/wiki/Digital_camera 

Data

The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data (plural of "datum") are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which information and then knowledge are derived. Raw data, i.e. unprocessed data, refers to a collection of numbers, characters, images or other outputs from devices that collect information to convert physical quantities into symbols.
Source: http://en.wikipedia.org/wiki/Data

Computer

A computer is, at its most basic, a machine which can take instructions, and perform computations based on those instructions.
Source: http://www.wisegeek.com/what-is-a-computer.htm

Circuit Board

Commonly known as PCBs (printed circuit boards), circuit boards consist of an insulator (usually fiberglass), with threads of conductive material serving as wires on the base of the board. The insulator may consist of one or numerous layers of material glued into a single entity. These additional layers may serve a number of purposes, including providing grounding to the board.

Source: http://www.wisegeek.com/what-is-a-circuit-board.htm

Central Processing Unit (CPU)

Also known as the Central Processing Unit or processor, the CPU is essentially the “brains” of your computer. Without the CPU, you wouldn’t be able to play games, type research papers, or surf the Internet. Your computer would basically be a very expensive paperweight.

Biometrics

Biometrics consists of methods for uniquely recognizing humans based upon one or more intrinsic physical or behavioral traits. In computer science, in particular, biometrics is used as a form of identity access management and access control. It is also used to identify individuals in groups that are under surveillance.

Source : http://en.wikipedia.org/wiki/Biometrics