Beginner Topic 10 of 51 Algorithms
Insertion Sort
Growing a sorted prefix by inserting each next element.
How it works
Insertion sort takes each element and shifts it left into its correct place among the sorted prefix. It is O(n²) worst case but O(n) on nearly sorted data and stable.
Where it is used
Small arrays, final pass inside hybrid sorts like Timsort.
Common pitfall
Quadratic on reversed input.
Where it fits in the course
Insertion Sort is topic 10 of 51 in Algorithms, rated Beginner. It follows Selection Sort. The next topic is Merge Sort.
Practice and explore
- Open the interactive lesson, with a mini quiz.
- Take the Algorithms quiz.
- Explore the Sorting Algorithms visualizer: Bubble, selection, insertion, merge and quick sort animated.
How to study this topic
- Read the explanation above and restate the definition in your own words.
- Open the interactive lesson and answer its mini quiz.
- Read the common pitfall, then write a short example that avoids it.
- Check your understanding in the Algorithms quiz, and revisit the topic if you miss a question.
Frequently asked questions
What is Insertion Sort?
Growing a sorted prefix by inserting each next element. It belongs to Algorithms and is a beginner-level topic.
Where do people use Insertion Sort?
Small arrays, final pass inside hybrid sorts like Timsort.
What is the most common mistake with Insertion Sort?
Quadratic on reversed input.
What should I learn before this topic?
Start with Selection Sort, the topic just before it in Algorithms.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Algorithms quiz. You can also explore Sorting Algorithms in the Visual Lab.
Is Insertion Sort hard to learn?
It is a Beginner topic, so it works as an entry point. If the terms are new, read the explanation twice and try the visualizer before the quiz.
How long does it take to learn Insertion Sort?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to Insertion Sort?
Selection Sort, Merge Sort, Bubble Sort are closely connected. The full list is in the related topics section of this page.
What should I study after Insertion Sort?
Continue with Merge Sort, the next topic in Algorithms.
Related topics
- Selection Sort (Algorithms)
- Merge Sort (Algorithms)
- Bubble Sort (Algorithms)
- Quick Sort (Algorithms)