This chapter first introduces the development history of web crawlers, the general process of crawling, the four main types and characteristics of web crawlers, and the Python library functions and frameworks needed to implement the crawling process. It then introduces the cutting-edge technology of web crawlers and the latest developments in website anti-crawling technology. Finally, this chapter presents an analysis conducted on job data crawled from Zhaopin.com , focusing on salary trends, work experience, and education requirements for positions in Beijing related to natural language processing, computer vision, backend, frontend, and big data engineering.