Hello,
Web Robots are programs that traverses the World Wide Web in an automated manner. Search engines (like Google, Yahoo etc.) use web crawlers to index the web pages to provide up to date data. How the web robots works?
Web robots, also known as web crawlers or spiders, work by systematically browsing the internet and collecting information from web pages. Here's a general overview of how web robots work:
1. Seed URLs: Web robots start by being provided with seed URLs, which are the initial web pages to be visited.
2. HTTP Requests: The web robot sends HTTP requests to the web servers hosting the web pages, asking for the page content.
3. Page Retrieval: Once the web server responds, the robot retrieves the HTML content of the web page.
4. Parsing: The robot parses the HTML to extract links to other web pages. It then adds these links to a queue of pages to visit.
5. Page Processing and Indexing: The robot processes the retrieved web page, extracting relevant data such as text, images, meta information, etc. This data is indexed and stored in the search engine's database.
6. Follow Links: The robot continues this process by following the links it has collected from the parsed pages, visiting new pages and adding more links to its queue.
7. Respect Robots.txt and Meta Tags: Web robots also adhere to the rules set by the `robots.txt` file and meta tags in web pages, which can specify which parts of a website should not be crawled.
8. Crawl Delays and Politeness: Some web robots implement crawl delays and other politeness measures to avoid overloading web servers with too many requests in a short period of time.
9. Update Index: Finally, the collected data is used to update the search engine's index, ensuring that the search results are up to date.
10. Handling Dynamic Content: Web robots are capable of handling dynamic content on web pages, such as JavaScript-generated content or interactive elements. This allows them to access a wide range of web content, including modern web applications.
11. Recrawl Frequency: Search engine web robots have algorithms to determine how frequently to revisit a particular web page for updates. Pages with frequent changes may be visited more often, while static pages may be revisited less frequently.
12. Multithreading and Parallel Processing: To efficiently crawl a large number of pages, web robots often use multithreading and parallel processing to fetch multiple pages simultaneously, speeding up the crawling process.
13. Duplicate Content Handling: Web robots also have mechanisms to detect and handle duplicate content, ensuring that only unique and relevant information is included in the search engine index.
14. Sitemap Parsing: Some web robots also look for XML sitemaps on websites, which provide a list of URLs for the robot to crawl, along with additional metadata about each URL. This helps the robot discover important pages more efficiently.
15. Robots Exclusion Protocol: Web robots respect the Robots Exclusion Protocol, which allows website owners to specify which areas of their site should not be accessed by web crawlers. This is typically done through the `robots.txt` file.
16. User-Agent String: When making requests to web servers, web robots identify themselves with a user-agent string, which allows website administrators to recognize and control the behavior of specific robots accessing their site.
17. Information Extraction: In addition to indexing text and images, web robots may also extract other types of data, such as structured information from web pages, including product prices, reviews, and contact details. This structured data can be used for rich snippets in search results and other applications.
18. Respecting Crawl Budget: Web robots are mindful of the crawl budget allocated to them by website owners. They aim to utilize this budget effectively by prioritizing important or updated pages, avoiding wasting resources on low-value or non-essential content.
19. Link Analysis: Some web robots perform link analysis to determine the importance of a web page based on the number and quality of links pointing to it. This helps search engines understand the relevance and authority of different pages on the web.
20. Geographical Considerations: For search engines with regional versions, web robots may prioritize crawling and indexing web pages relevant to specific geographical regions, in order to provide more localized search results.
21. Adherence to Web Standards: Web robots follow web standards and best practices to ensure that they can effectively interpret and process the content of web pages, regardless of the technologies used to create them.
22. Monitoring Changes: Web robots continuously monitor changes on web pages, allowing search engines to update their indexes with the most recent information and reflect current trends and events on the web.
23. Handling Large-Scale Data: Web robots are designed to handle the enormous volume of data available on the web and are optimized for scalability to process and index a vast number of web pages efficiently.
24. Adaptation to New Technologies: Web robots are constantly updated to adapt to new web technologies and standards, allowing them to effectively crawl and index the latest web content, including dynamic and interactive elements.
25. Malware and Security Considerations: Web robots may also incorporate security features to detect and avoid accessing malicious or infected web pages to protect both the search engine's infrastructure and end users.
26. Respect for Privacy and Robots Meta Tag: Web robots also consider privacy concerns and adhere to the instructions specified by the Robots Meta Tag, which can indicate whether a page should be indexed or not, or if links on the page should be followed or not.
27. Discovery of New Content: Web robots use various mechanisms to discover new content, such as following links from known pages, submitting forms, and using APIs provided by websites to access structured data.
28. Regular Maintenance and Monitoring: Search engines continuously maintain and monitor their web crawling infrastructure to ensure that it operates effectively, efficiently, and in compliance with web standards and best practices.
29. Respecting Website Policies: Web robots respect the policies and guidelines set by website administrators through mechanisms like the robots.txt file and meta tags, ensuring that they only access content that the website owner allows.
30. Mobile-First Crawling: In response to the increasing prevalence of mobile devices, search engines have adapted their web crawlers to prioritize the indexing of mobile-friendly web pages, following Google's move to a mobile-first indexing approach.
31. Content Quality Evaluation: Web robots can also analyze the quality and relevance of content on web pages, contributing to search engine ranking algorithms that aim to present high-quality and authoritative content to users.
32. Crawl Budget Optimization: Advanced web robots are designed to optimize their crawl budget by prioritizing essential pages, avoiding duplicate content, and efficiently discovering new and updated content.
33. Natural Language Processing: With advancements in natural language processing, web robots can better understand and index the semantic meaning of web content, leading to more accurate and contextually relevant search results.
34. Structured Data Recognition: To improve search result presentation, web robots identify and index structured data such as schema.org markup, which provides additional context and information about the content of web pages.
The evolution of web robots continues to be driven by technological advancements and the need to provide users with the best possible search experience. As web content becomes increasingly diverse and dynamic, web robots play a crucial role in organizing and presenting this information to users worldwide.
There are a variety of robots that work in a variety of different ways. In order to answer this question completely the type of robot would have to be known. A few types are electrical, computerized, and remote.
Typical behavior for a robot includes: completing multi-step (often repetitive) tasks, moving, mimic humans, using tools to complete a task, and showing many other signs of seeming intelligence. For now, the appearance of intelligence is just that, appearance. This means that the first key in understanding how a robot works is understanding the process for which it has been designed. A robot works to fulfill a programmed purpose, even if that purpose is to act as human as possible.
Well, this thread is not about robots... Its about Search engine bots.
And, to the O.P. try to use search bar in the search engines. Wikipedia has huge information for this.
http://en.wikipedia.org/wiki/Web_crawler