Blocking and CAPTCHA verification elements are measures by which website operators prevent automated access. They take the form of limiting the number of requests from one address, temporary blocking, a requirement to verify that the visitor is human, or outright refusal of access. From a company's point of view, their presence is above all a clear expression of the operator's will that they do not want automated collection. Circumventing them is therefore not merely a technical task but moves the activity into risky territory with regard to both the terms of use and the legal protection of databases. The legitimate approach is to reduce the intensity of collection, approach the operator with a request for access to the data, or look for another source – including official interfaces and open data, which often provide the same information.
See also: Legal aspects of scraping, Database protection, Rate limiting and ethical scraping.
