# Chapter 12 - Summary¶

Chapter 12 included the following concepts from computing.

• Block of Code - A block of code in Python is one or more code statements that are part of a loop, conditional, function, or procedure.
• Boolean Expression - A Boolean expression is one that is either true or false. This is also called a logical expression.
• Complex Conditionals - A complex conditional has two or more logical expressions joined by the keywords and, or, or not.
• Condition - A condition is something that is either true or false. This is also called a Boolean expression or a logical expression.
• Conditional Execution - Conditional execution means that one or more statements are executed only when a condition (logical expression) is true. This is also called a conditional. The statements that are executed when the condition is true are called the body of the loop.
• Decision - A decision is a choice between at least two choices.
• Flowchart - A flowchart is a diagram that shows the execution paths for a program. The conditionals are shown as diamonds.
• Logical Expression - A logical expression is one that is either true or false, like x == 3 which will return true if x is equal to 3. This is also called a Boolean expression.
• Negation - When you negate a logical expression if the original expression is true the negated expression is false and if the original expression is false the negated expression is true.

## Summary of Python Keywords and Functions¶

• And - The keyword and is used to join two logical expressions and then both of the logical expressions must be true for the joined expression to be true.
• Else - The keyword else is used to execute one or more statements in a block following the else when the condition in the if part of the statement is false. An else must always have an if statement before it.
• If - The Python keyword if is used to start a condition. It is followed by a Boolean expression and then has one or more statements in the body of the loop that are executed only if the Boolean expression is true.
• Not - The keyword not is used to negate a logical expression. If the original expression is true the negated expression is false and if the original expression is false the negated expression is true.

Note

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Next Section - Chapter 12 Exercises