Web scraping is the act of programmatically harvesting data from a webpage. It consists of finding a way to format the URLs to pages containing useful information, and then parsing the DOM tree to get at the data. It’s a bit finicky, but our experience is that this is easier than it sounds. That’s especially true if you take some of the tips from this web scraping tutorial.
It is more of an intermediate tutorial as it doesn’t feature any code. But if you can bring yourself up to speed on using BeautifulSoup and Python the rest is not hard to implement by trial and error. [Hartley Brody] discusses investigating how the GET requests are formed on your webpage of choice. Once that URL syntax has been figured out just look through the source code for tags (css or otherwise) that can be used as hooks to get at your target data.
So what can this be used for? A lot of things. We’d suggest reading the Reddit comments as there are several real world uses discussed there. But one that immediately pops to mind is the picture harvesting [Mark Zuckerburg] used when he created Facemash.