Spider
01 Definition
Spider meaning: Another name for a web crawler that follows links across the web.
Spider is an older term for a web crawler, software that moves from page to page by following links, much like moving across a web. The name and crawler are used interchangeably. Search engines rely on spiders to discover and read content for their indexes.
Also called
Why it matters
How Spider fits the work
The term still appears in SEO discussion and tools, so recognizing that a spider and a crawler are the same thing avoids confusion when reading documentation.
In context
The developer noted that the search spider could not follow links built only with JavaScript onclick events, so those pages went undiscovered.
Practical note
Spider and crawler mean the same thing; there is no functional difference. Statements about how spiders crawl and render pages apply equally to any crawler.