Depth-first search (DFS) is a popular algorithm used to explore and traverse data structures like trees and graphs. It starts at a given node, called the root, and explores as far as possible along each branch before backtracking. This means that DFS goes deep into one path until it can’t go any further, then it retraces its steps to explore other paths. DFS can be implemented using a stack, either explicitly or through recursion. It’s useful for tasks like finding a path in a maze or solving puzzles. However, it may not always find the shortest path, as it prioritizes depth over breadth.