Ever wondered how search boxes suggest words as you type? Or how a spell checker knows what you probably meant to write?

Behind the scenes, there's a powerful but often underrated data structure making it all possible: theTrie (pronounced "try").

Let’s take a look 👇

🔠 What Is a Trie?

ATrie, also known as aprefix tree, is a tree-like data structure used to store a dynamic set of strings — especially useful forprefix-based lookups.

Each node in a trie represents a character, and by connecting nodes from top to bottom, you can represent entire words.

🧠 Real-World Use Cases

Tries shine when you’re dealing with words, prefixes, or partial matches. You’ll find them behind:

• Autocomplete and search suggestions(e.g. Google search, VSCode IntelliSense)
• Spell checkers and correctors
• IP routing (longest prefix matching)
• Word games like Boggle or Scrabble solvers
• Dictionary or keyword matching systems

🔍 Why Not Just Use an Array or Hash Table?

Let’s say you have a list of 100,000 words. If you want to find all words that start with"cat", a trie can do thatfaster and more efficiently than scanning every word in an array or using a hash table.

Why? Because the structure of a trienaturally groups words by their prefixes, making lookups almost instantaneous.

⚙️ How It Works (At a High Level)

• Each node represents a single character.
• Children nodes represent possible next characters.
• Words are built by walking down from the root node.
• A special flag marks the end of a valid word.

Example: Storing "cat" and "car"

(root)/\c...|a/\tr

From the root,"c" leads to"a", which leads to"t" or"r" — forming "cat" and "car".

🚀 Benefits

• Fast prefix searches (often O(k), wherek is the length of the word)
• Efficient memory usage for shared prefixes
• Flexible: can be extended to support wildcard matching, autocomplete ranking, etc.

🤔 When to Reach for a Trie

• You’re implementing a feature based onprefix matching
• You need to dolots of lookups from a large dictionary of words
• You want to build something like autocomplete, spellcheck, or typeahead

🧠 TL;DR

• ATrie is a tree-like data structure designed for efficientprefix-based string matching.
• It powers real-world features likeautocomplete,search suggestions, andspellcheckers.
• If you’re dealing with lots of strings and care about prefixes —Tries are worth knowing.