An object whose instance variables contain invalid values.
An error in a program.
Bugs are unintentional.
A situation or value that is at or near some "boundary". For example, boundary cases for a string of seven characters would include the first and last characters or positions in the string, along with illegal positions -1 and 7.
The sequence of statements that are executed as the result of running a program.
Test for illegal input or for inconsistencies in a program that are likely symptoms of bugs.
Executed by evaluating the boolean expression that immediately follows the word "if"; if the resulting value is true, the statements in the body of the then are executed, otherwise the statements in the body of the else are executed.
One of the following operators used to compare two values: < (is less than), <= (is less than or equal to), > (is greater than), >= (is greater than or equal to), == (is equal to), and != (is not equal to).
Modulus is an arithmetic operation in which numbers "wrap around" after a certain value is reached. The modulus operator takes two numbers, and returns the remainder after the second number is divided into the first number as many times as possible.