Types are classifications of objects, which is what Python, as an OOP language, deals with. They determine how those objects are dealt with (for example, adding two integers results in an integer, two strings results in a concatenated string, and an integer and a string results in an error).

 

An expression is composed of objects (or operands) and operators, and can be interpreted into a value.

 

A type conversion turns one type of object into another. For example, applying str to the integer 3 results in the string '3'.

 

Keywords are words that have special meanings within a language. Many editors will display them in special colors. These words cannot be used as variables.

 

A straight line program simply goes through and carries out each step. A branching program will do different things depending on conditions set within the program.

 

A conditional statement starts with an if statement, and can also include elif and else statements.