Understanding HTML Basics for Web Scraping
Before extracting data from websites through web scraping, it’s essential to understand how websites are structured. Most websites are built using HTML (Hypertext Markup Language), which describes the structure and content of a webpage, including which elements are visible, which can be linked, and how the content connects.
The Basic Structure of HTML
An HTML document consists of different areas marked by tags. These tags typically have an opening tag (like <tag>) and a closing tag (like </tag>). The basic structure includes:
- A DOCTYPE declaration that tells the browser this is an HTML5 document
- The <html> tag that contains everything else
- A <head> section for metadata like the title and character encoding
- A <body> section that contains everything visible on the page
Inside the body, various elements like headings (<h1>, <h2>, etc.) and paragraphs (<p>) define the content that appears on the page.
Inspecting HTML in the Browser
To examine a website’s HTML code, you can use the browser’s inspector tool:
- Right-click on any part of a webpage
- Select ‘Inspect’ or ‘Inspect Element’
- The inspector panel will open, displaying the HTML structure
One particularly useful feature is the element selector tool (usually an icon in the inspector panel). When activated, you can click directly on any visible element of the page, and the inspector will automatically highlight the corresponding HTML code.
Important HTML Elements for Web Scraping
Several HTML elements are particularly relevant for web scraping:
Tables
Tables are often used to present structured data like statistics or lists. Each table consists of:
- <table> tags that define the entire table
- <tr> tags for table rows
- <th> tags for table headers
- <td> tags for table data cells
Links
Links are defined with the <a> tag and include an href attribute that specifies the URL they point to. For example: <a href=”https://example.com”>Link text</a>
Classes and IDs
Classes and IDs help identify specific elements:
- Classes (defined with the ‘class’ attribute) can be applied to multiple elements and are useful for selecting groups of similar items
- IDs (defined with the ‘id’ attribute) must be unique within a page and are ideal for selecting specific individual elements
Understanding these concepts provides the foundation needed to effectively extract data from websites using tools like Beautiful Soup, which will be covered in subsequent discussions.