What radix sort is
Radix sort is a sorting algorithm that orders numbers by looking at their digits one position at a time, rather than by comparing whole numbers directly. It processes the items in several passes, each pass sorting based on a single digit position. By handling the digits in the right order, radix sort gradually builds up a fully sorted result. It is a non-comparison sorting method.
Processing one digit at a time
The central idea of radix sort is to sort by individual digit positions. In each pass, the items are grouped according to the digit at the position being considered. For example, the algorithm might first sort by the last digit, then by the next digit, and so on. Each pass considers just one digit position across all the items.
Building up the order
Radix sort works because sorting by each digit position in the proper sequence, while keeping the relative order from earlier passes, results in a fully sorted list. After the final digit position has been processed, the numbers end up correctly ordered. The order emerges from the accumulation of the per-digit passes rather than from direct comparisons.
When radix sort is fast
Radix sort can be very fast, especially when the numbers have a limited number of digits, because the number of passes depends on the digit count rather than on comparing items. It relies on an efficient way to group items by a single digit in each pass. In the right conditions, this makes it competitive with or faster than comparison-based sorts.
Why radix sort matters
Radix sort matters because it is another example of sorting without direct comparisons, and it can be highly efficient for suitable data such as fixed-length numbers. Understanding radix sort clarifies how processing data digit by digit, one position at a time, can produce a sorted result quickly, broadening the picture of how sorting can be done.
Why it matters
Radix sort is a notable non-comparison sorting algorithm. Understanding what it is - sorting numbers digit by digit across passes - clarifies an efficient, comparison-free way to order data. For anyone interested in computer science, it is a valuable concept to understand.
Related on Skillo
See also: What is counting sort? Explained, What is a sorting algorithm? Explained.
Sources
Published date reflects the original event date (2026-10-20). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.
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