Web crawlers, bots, are software programs that visit websites and collect data automatically. Web crawlers are often used to collect data for search engines, such as the Google search engine. A web crawler starts with a list of URLs to visit, called a seed list. As the crawler visits each website, it identifies all the links on the page and adds them to the list of URLs to visit, called the crawl frontier. The crawler continues visiting web pages and adding links to the crawl frontier until it has visited all the URLs in the seed list.
A web crawler can be programmed to collect any type of data from a website. Common data that is collected by web crawlers include title tags, meta tags, and body text. Web crawlers can also collect images, videos, and other files.
Natural language processing (NLP) is a subfield of artificial intelligence that deals with analyzing, understanding, and generating human language. NLP is used to extract information from text documents automatically. For example, NLP can automatically generate summaries of text documents or identify key phrases in a document.
NLP algorithms often process and analyze unstructured data, such as text documents. NLP algorithms can perform various tasks, such as text classification, named entity recognition, part-of-speech tagging, parsing, and machine translation.
Machine learning is a subfield of artificial intelligence that deals with constructing and studying algorithms that can learn from data. Machine learning is often used to develop predictive models. Predictive models are mathematical models used to predict the probability of an event occurring. For example, a predictive model could predict the probability of a customer making a purchase.
Machine learning algorithms can automatically learn and extract information from data sources that are not explicitly labeled or categorized. For example, a machine learning algorithm could automatically identify products in images.
References:
https://en.wikipedia.org/wiki/Web_crawler
https://en.wikipedia.org/wiki/Natural_language_processing
https://en.wikipedia.org/wiki/Machine_learning