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Add List Items

3 min read ·

Adding items to a list is one of the most common operations in Python. Because lists are mutable, you can insert new elements at any position—beginning, middle, or end.
This topic covers all valid ways to add items to a list, with clear examples and edge cases.

Add Items Using append()

The append() method adds one item to the end of the list.

Add Items Using insert()

The insert() method adds an item at a specific index.

Syntax

Add Multiple Items Using extend()

The extend() method adds multiple items from another iterable.

Add List to Another List (Important Difference)

Using append()

Result is a nested list.

Using extend()

Result is a single flat list.

Add Items Using List Concatenation (+)

Original lists remain unchanged.

Add Items Using Slice Assignment

Add Items in a Loop

Add Items Conditionally

Add Nested Items

Common Mistakes

Expecting append() to Add Multiple Items

This adds a list inside a list.

Using Wrong Index in insert()

Python inserts at the end, not an error.

Performance Tip

  • append() is fast and preferred
  • insert() at the beginning is slower for large lists
  • extend() is best for adding many items
This topic naturally leads to:
  • Remove List Items
  • List Copying
  • List Comprehensions
  • List Performance Tips