Web Crawler

A web crawler systematically discovers and follows links across a site or the broader internet to build an index. Commonly known as a crawler bot or spider, this automated system maps the topology of the web by resolving DNS records, parsing HTML documents, and extracting href attributes to map out navigation paths. Search engines like Google and Bing rely on these systems to feed their global indexes.

While the terms are often used interchangeably in casual speech, a web crawler vs web scraper distinction is crucial in data engineering. A crawler focuses on discovery and link traversal, whereas a scraper targets specific pages to extract structured fields. A typical web crawler example involves crawling an entire e-commerce domain to collect a master list of product URLs, which are then passed to an extraction pipeline. Understanding how a web crawler works is foundational when building any data collection infrastructure, as discovering URLs is the necessary precursor to extracting data.

Key Specifications & Comparison

Understanding the technical boundaries between crawling and scraping determines your infrastructure choices.