Binary is an alternative number system which works very well for computers. Humans have ten fingers; that's probably why we use ten digits (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) in our number system (decimal), but it is easier for a computer to use only two digits (0 and 1). Ones and zeros can be represented with high or low voltage, closed or open switches, aligned or misaligned magnetic particles, etc. A byte is a group of eight bits, and it is the standard unit by which data is stored. There are 256 different combinations of zeros and ones you can make with one byte, from 00000000 to 11111111. This is enough to cover all the ASCII characters. If more than 256 values are needed, then more than one byte can be used. With two bytes, there are 65536 possible combinations of ones and zeros. These bytes can represent any kind of data. For example, a picture may be made up of thousands of pairs of bytes, with each pair of bytes representing a single dot in one of 65536 colors. Put together all these dots (known as pixels) and you have a full-color picture (most picture data is also compressed). On systems using Microsoft Windows, the meaning of data stored on a disk is determined by the file's extension. For example: if it is TXT, then it is ASCII text; if it is EXE, then it is a program (an executable).
A byte is eight binary digits. It is the smallest unit a computer works with at once. The bits of a byte can be individually modified, but a computer still works with at least one byte at a time. See also: Binary and my article on Bits and Bytes.
A button does some command in a program when it is clicked. Buttons usually have a 3-dimensional look, although you may have to move the mouse over the button for it to look 3D. You should single-click on buttons (do not double-click).
Compact Disc Recordable. A special type of compact disc which can have information written onto it once. You must have a special CD-R drive to write to these discs, but most CD-ROM drives can read them.
To make a window active by bringing it to the front.