What are Spiders, Robots and Crawlers and what are their functions?
 

Spiders, Robots and Crawlers all are same these are automated software program search engine use to stay up to date with web activities and finding new links and information to index in their database.
All the three programs Spiders, Robots and crawlers are same and do similar work we call them with different names these are only service tools for search engine which helps to find and index new web links in search engine correctly.

Googlebot is the software used by Google to fetch and render web documents collectively. They crawl each web page and its contents and store them in the Google index under the relevant keywords of the website. Google bots are also known as Spiders and Crawlers.

I think you should Google it for the better results because there are plenty of articles for this and in this forum, there is also so many threads to this post. So, it would be better to try a search in FAQ section first instead of creating the spammy threads again and again and again.

Spider - The browsers are like a program and to download the web page.

Crawler – The program is automatically to follow the links are web page..

Robots - It had automated computer program can visit websites. It will guided by search engine algorithms It can combine the tasks of crawler & spider helpful of the indexing the web pages and through the search engines.

Spiders and crawlers are responsible for indexing and retrieving results in search results of a Search Engine. Google Bot is the crawler of Google.

Spiders, Robots and Crawlers all are same these are automated software programme search engine use to stay up to date with web activities and finding new links and information to index in their database.

What are Spiders, Robots and Crawlers and what are their functions?
 

Spiders, Robots and Crawlers all are same these are automated software programme search engine use to stay up to date with web activities and finding new links and information to index in their database.
Web crawlers (also called 'spiders', 'bots', 'spiderbots', etc.) are software applications whose primary directive in life is to navigate (crawl) around the internet and collect information, most commonly for the purpose of indexing that information somewhere.