3)Python - Variable Types:

Variables:
Variables are reserved memory locations to store values. Which means that when you create a variable, will reserve some space in memory.

Note:
Python variables do not need explicit declaration to reserve memory space other languages like Java,C etc.,
The declaration happens automatically when you assign a value to a variable. The equal sign (=) is used to assign values to variables.

So, in-turn, we should only focus on assignment of variable.

Two ways of assignments:

1. Single variable assignment
2. Multiple variable assignment

Example:

Python Standard Data Types:

Python has five standard data types

1. Numbers
2. String
3. List
4. Tuple
5. Dictionary

1.Numbers:

Number data types store numeric values.

Python supports four different numerical types

• integers -> a=15
• long integers -> a=1888L
• floating point -> a=9.8
• complex numbers -> a=1+2j

Note:

A complex number consists of pair of real floating-point numbers denoted by x + yj, where x and y are the real numbers and j is the imaginary unit.

2.Strings:

Strings are contiguous set of characters represented in the quotation marks either single or double.

Subsets of strings can be taken using the slice operator ([ ] and [:])

3.List:

A list contains different type of items are separated by commas and enclosed within square brackets ([]).

The values stored in a list can be accessed using the slice operator ([ ] and [:]) with indexes starting at 0 and to end -1. 

4.Tuple:

• Tuples are similar to Lists unless it is read-only.
• A tuple consists of a number of values separated by commas and enclosed within parentheses().

The main differences between lists and tuples: 

• Lists are enclosed in brackets ( [ ] ) and their elements and size can be changed,
• Tuples are enclosed in parentheses ( ( ) ) and cannot be updated.

Note:

The tuples improves the read access for large data-set operations.

5.Dictionary:

Python's dictionaries are kind of hash table type and consist of key-value pairs.

Enclosed by curly braces ({ }) and values can be assigned and accessed using square braces ([]).