Chapter 2 - Variables and Expressions

• Variable - named item, such as x or num_people, that holds a value
• assignment statement - assigns a variable with a value
• Incrementing - increasing a variable's value
• Identifier - aka name, is a sequence of letters, underscores, and digits, and must start with a letter or an underscore
• object - represents a value and is automatically created by the interpreter when executing a line of code
• garbage collection - deleting unused object
• name binding - process of associating names with interpreter objects
• value: "20", "abcdef", or "55"
• type: a type of the object, such as int or str
• identity: a unique identifier that describes the object
• mutability: indicated whether the object's value is allowed to be changed (int and str are immutable)
• floating-point number is a real number with decimal point
• floating-point literal is written with the fraction part even if that fraction is 0, like 1.0, 0.0, or 99.0
• compound operators - provide a shorthand way to update a variable, such as +=1, being shortened for age = age + 1
• Overflow occurs when a value is too large to be stored in the memory allocated by the interpreter
• expression - a combination of items, like variables, literals, operators, and parentheses, that evaluates to a value
• literal - a specific value in code like 2
• an operator is a symbol that performs a built-in calculation, which performs addition
• module - a file containing Python code that can be used by other modules or scripts
• a module is made available for use via the import statement
• once a module is imported, any object defined in that module can be accessed using dot notation
• Python comes with a standard math module to support such advanced math operations
• A function is a list of statements that can be executed simply by referring to the function's name
• the item passed to a function is argument
• random module provides methods that return random values
• seed - help generate a random number
• Python uses Unicode to represent every possible character as a unique number, known as code point
• a script is a file containing Python code that is passed as input to the interpreter
• A module is a file containing Python code that is imported by a script, module, or interactive interpreter
• A dot notation is used to reference an object in an imported module
• An import is to execute the contents of a file containing Python code and make available the definitions from that file
• __name__ is to determine if the file was executed as a script by the programmer or imported by another module