Please tell me what are spiders. Robots and crawlers and their functions.

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

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

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

Thanks dear @sinelogixtech but these all are same whose work is to collect information world wide and send to the database.

Quote from: sinelogixtech on May 01, 2017, 03:30:43 AM
Spider - The browsers are like a program and to download the web page.

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

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

They are all the same and are search engine automated programs that are responsible to read through webpage source to provide information to search engines.

They all are related to Search Engine and they are same.These are the automatic and mathematical program which visits worldwide  thousands of webpages.