What is a List?

A list in Python is a collection data type that allows you to store multiple values in a single variable. These values can be of any type: integers, strings, floats, booleans, or even other lists.

When Should You Use a List?

Use a list when:

• You want to store a group of items as a single unit. For example, storing the names of all students in a class.
• Order matters — the sequence in which elements are added to the list is preserved. This is useful when processing data in the same order as it was collected.
• You want to allow duplicate values. Lists support repeated elements, so values like [10, 10, 20] are valid.
• You want the flexibility to add, remove, or modify the items later. Lists are mutable, which means they can grow or shrink dynamically as your program runs.

List Characteristics

Feature	Description
Ordered	Yes. Elements are stored in the order they are inserted. Access by position is possible using indexing.
Allows Duplicates	Yes. The same value can appear multiple times. This is helpful when data repetition has significance.
Mutable	Yes. Lists can be changed after creation — you can add, remove, or modify elements using built-in methods like append(), remove(), or direct assignment.
Indexing Supported	Yes. Both positive indexing (from the start) and negative indexing (from the end) are supported.
Slicing Supported	Yes. You can extract sublists using slice notation like list[start:end].
Heterogeneous Elements	Yes. Lists can store a mix of different data types like [10, "Durga", 3.14, True].
Syntax	Lists are defined using square brackets [] and elements are separated by commas. Example: [1, 2, 3]

Creating a List

You can create a list by placing values inside square brackets:

l = [10, "Durga", 10, 20, 30]
print(l)             # Output: [10, 'Durga', 10, 20, 30]
print(type(l))       # Output: <class 'list'>

Accessing List Elements

You can access list elements using indexing. Indexes start from 0.

print(l[0])          # 10 (first element)
print(l[-1])         # 30 (last element)

You can also access a range of values using slicing. Slicing returns a new list.

print(l[1:4])        # ['Durga', 10, 20]

Here, 1:4 means start at index 1 (inclusive) and go up to index 4 (exclusive).

List is Mutable

You can modify the contents of a list by directly assigning a new value to a specific index:

l[0] = 7777
print(l)             # [7777, 'Durga', 10, 20, 30]

This demonstrates that lists are mutable, meaning their contents can be changed in place.

Adding Elements to a List

You can add elements to the end of a list using the append() method:

l = []
l.append(10)
l.append(20)
l.append(30)
l.append(40)
print(l)             # [10, 20, 30, 40]

You can add any type of value, and the order of insertion will be preserved.

Removing Elements from a List

Use the remove() method to delete a specific element by value:

l.remove(30)
print(l)             # [10, 20, 40]

If the value occurs multiple times, only the first occurrence will be removed.

Creating an Empty List

To initialize a list with no elements:

empty_list = []
print(empty_list)    # []

This is useful when you’re building a list dynamically through loops or conditionals.

List is Growable

Lists can dynamically grow or shrink as needed. You can add elements using append() or insert(), and remove them using remove() or pop().

l.append(50)         # Add new element
l.remove(10)         # Remove an element
print(l)             # [20, 40, 50]

This dynamic resizing makes lists extremely flexible for data manipulation.