Publisher Summary This chapter discusses fundamentals of matrix laboratory (MATLAB) that includes: variables, operators, and expressions, arrays, basic input and output, repetition (for), and decisions (if). Variables are fundamental to programming. Variable consists of two rules: It consists only of the letters a–z, the digits 0–9, and the underscore (_), and it starts with a letter. MATLAB is also case-sensitive, which means it distinguishes between upper- and lowercase letters. MATLAB is described as an expression based language because it interprets and evaluates typed expressions. Expressions are constructed from a variety of things, such as numbers, variables, and operators. There are two straightforward ways of getting output from MATLAB: (a) entering a variable name, assignment, or expression on the command line, without a semicolon; (b) using the disp statement. The MATLAB desktop consists of a number of tools: the Command Window, the Workspace browser, the Current Directory browser, and the Command History window. The Workspace browser on the desktop provides a handy visual representation of the workspace. Clicking a variable in it invokes the Array Editor, which may be used to view and change variable values.