What is the difference between Spiders, Robots and Crawlers?

[Patelsharp]

What is the difference between Spiders, Robots and Crawlers.

[RH-Calvin]

They are all the same - the different names of a search engine program that reads your webpage source file to cache and index in search engines.

[ketul]

All are same but name is different.

[Rajan Verma]

Spider - a browser like program that downloads web pages.

Crawler – a program that automatically follows all of the links on each web page.

Robots - An automated computer program that visit websites & perform predefined task. They are guided by search engine algorithms & are able to perform different tasks instead of just one crawling task. They can combine the tasks of crawler & spider together and help in indexing and ranking of websites on any particular search engine.

[Harikrishna Patel]

Spider, crawler and robots are Google software that visit the website and put detail in their database it frequently visit website and update their database if you make some change on your website.

[capsuleseo]

Spider Scan and judge you website content ,Crawler crawl you content and index it in there searches according to Inbound links both techniques helps google to judge importance of website in terms of ranking ,robot.txt file is that file which is included into web coding so that google not consider it in crawling or to hide page from google crawling .