The statements and instructions that a programmer writes when creating a program. One line of this "source code" may generate one machine instruction or several depending on the programming language. A line of code in assembly language is typically turned into one machine instruction. In a high-level language such as C++ or Java, one line of code may generate a series of assembly language instructions, resulting in multiple machine instructions.
Lines of Code Are Not the Same
One line of code in any language may call for the inclusion of a subroutine that can be of any size, so while used to measure the overall complexity of a program, the line of code metric is not absolute. Comparisons can also be misleading if the programs are not written in the same language. For example, 20 lines of code in Visual Basic might require 200 lines of code in assembly language.
In addition, a measurement in lines of code says nothing about the quality of the code. A thousand lines of code written by one programmer can be equal to three thousand lines by another. See KLOC