What are the three types of scrapers?

Web scraping refers to automatically extracting data from websites. There are three main approaches to scrape content from the web:

1. Parsing the DOM

Most modern websites are built using HTML, CSS, and JavaScript. These technologies construct the Document Object Model (DOM) - a structured representation of the page that lives inside the browser.

The simplest scraping technique is to use a language like Python to download the page content and parse through the DOM structure to extract the data you need.

For example, to scrape all the headlines from a news article, you would:

1. Fetch the page HTML
2. Parse the HTML to identify all <h1>, <h2> tags 
3. Extract just the text content of those tags

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2. Headless Browser Automation

To scrape dynamic webpages that load content dynamically, you can automate actions in a headless browser. Popular tools include Selenium, Playwright, and Puppeteer.

The headless browser fetches the page, runs any JavaScript, waits for network requests to complete, and then you can parse the final DOM. This allows scraping of content that gets added after page load.

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3. Using a Web Scraping Service

Lastly, instead of writing your own scrapers, you can use a pre-built web scraping platform. These are services that provide ready-made scrapers, proxies, browsers, and infrastructure to extract data at scale.

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So in summary - the three main approaches are direct DOM parsing, headless browser automation, and web scraping services. Pick the technique that best fits your use case and technical abilities.