# Python : Variables, Operators, Expressions and Statements

### Variables

As the name implies, a variable is something which can change. A variable is a way of referring to a memory location used by a computer program. A variable is a symbolic name for this physical location. This memory location contains values, like numbers, text or more complicated types.

Please note important point for Python. It does not have a command for declaring a variable. A variable is created the moment you first assign a value to it.

first_Name = 'your name'
y ='techTrekk'
n00b = 'ac'
un_der_scores = 'sample text'
###### Variables Naming convention
• Variables names must start with a letter or an underscore but not with number
• A variable name can contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
• Names are case sensitive.
casesensitive, CASESENSITIVE, case_sensitive and Case_Sensitive are each a different variable.
###### Variable naming

See Python PEP 8.

Function names should be lowercase, with words separated by underscores as necessary to improve readability. mixedCase is allowed only in contexts where that’s already the prevailing style

I personally Like camelCase/mixedCase used in JavaScript and hence I prefer to use the same in Python but you can take a call by yourself but make sure you stick with one style to maintain consistency.

Variable name chosen should be “mnemonic”, meaning, by variable name itself, reader should be able to understand what this variable is for. e.g. It is not convenient to store first name in first_name instead of abx123 or abc

### Operators

Operators are special symbols that represent computations like additions and subtraction. The value these operators are applied to are called as operands.

 Activity Symbol Addition + Subtraction – Multiplication * Division / Quotient // Reminder %

Python follows PEDMAS rule

### Expressions

An express is combination of values, variable and operators

>>> 1+4
5


### Statements

A statement is used to form the sequence of a program (e.g. if-then , while-do statements).

A statement can be simple or complex and can contain 0 or more expression