In order to scrape a website, we first need to download its web pages containing the data of interest, a process known as crawling. There are a number of approaches that can be used to crawl a website, and the appropriate choice will depend on the structure of the target website. This chapter will explore how to download web pages safely, and then introduce the following three common approaches to crawling a website:

• Crawling a sitemap
• Iterating each page using database IDs 
• Following web page links

We have so far used the terms scraping and crawling interchangeably, but let's take a moment to define the similarities and differences in these two approaches.