Web crawlers are tools that scan websites in order to acquire all of the data related to the website. Then, all of this data can be used to store data in a database. The most common use for crawlers is to create a database for a search engine. However, the database can be used for other methods as well, including marketing.
Crawling The Right URLs
In order to avoid crawling the same URLs thousands of times, crawlers will modify the URL after it has been crawled.