System Design Visualized
Lesson 9.3

DFS vs BFS

Play this lessonThis lesson comes with an interactive animation you can break, a live-code challenge and a chapter quiz.

The web is a directed graph: pages are nodes, hyperlinks are edges. Crawling is graph traversal. DFS is usually a bad choice because the depth can be enormous. Crawlers commonly use BFS with a FIFO queue. But plain BFS has two problems:

The rest of this lesson is part of Pro

Pro unlocks every lesson with its animation, code challenge and quiz, plus every interview problem. ₹299 a month or ₹1,999 a year.

See Pro

Remember it, then prove it

Create a free account to save your progress, get spaced-repetition reviews of what you miss, and design real systems in the interview simulator.

Start free