12 Questions
What is the primary function of a web crawler?
To send HTTP requests to a web server to retrieve data
What type of web crawler targets specific topics or websites?
Focused crawler
What is a common challenge faced by web crawlers?
Handling large amounts of data
What is the purpose of a robots.txt file?
To specify website restrictions on crawling
What is one application of web crawling?
Building and updating search engine indexes
What type of web crawler runs on multiple machines to increase crawling speed?
Distributed crawler
What is the primary purpose of API scraping?
To extract data from Application Programming Interfaces (APIs) using automated scripts or programs
Which type of API scraping involves extracting data from web APIs?
Web Scraping
What is required to access API endpoints?
API keys or authentication tokens
What is the purpose of parsing API responses?
To extract specific data using programming languages
What should you ensure when scraping APIs?
Respect API terms of service
What is a common challenge faced by API scrapers?
Handling API rate limiting
Study Notes
Web Crawling
Definition: Web crawling, also known as web spidering, is the process of automatically browsing the internet to gather data or information from websites.
How it Works:
- A web crawler, also known as a spider or bot, is a program that sends HTTP requests to a web server to retrieve data.
- The crawler follows hyperlinks from one webpage to another to discover new URLs.
- The crawled data is then stored in a database or file for further processing.
Types of Web Crawlers:
- Focused crawlers: Target specific topics or websites.
- General-purpose crawlers: Crawl a wide range of websites and topics.
- Deep web crawlers: Crawl the deep web, which includes content not indexed by search engines.
- Distributed crawlers: Run on multiple machines to increase crawling speed.
Challenges:
- Handling large amounts of data: Crawlers can generate massive amounts of data, making it difficult to store and process.
- Avoiding getting blocked: Websites may block crawlers to prevent abuse or data theft.
- Respecting robots.txt: Crawlers must respect website restrictions on crawling, as specified in the robots.txt file.
Applications:
- Search engines: Web crawlers are used to build and update search engine indexes.
- Data mining: Crawlers can be used to gather data for analysis and insights.
- Monitoring website changes: Crawlers can be used to track changes to websites over time.
Ethical Considerations:
- Respect website terms of use: Crawlers must comply with website terms of use and robots.txt files.
- Avoid overwhelming websites: Crawlers should avoid sending too many requests to a website, which can cause server overload.
- Respect user privacy: Crawlers should not collect personal data or violate user privacy.
Understand the basics of web crawling, including how it works, types of web crawlers, challenges, applications, and ethical considerations. Learn about the role of web crawlers in search engines, data mining, and website monitoring.
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