It only takes half a second for Google to return a search based on keywords you type in, but there’s a whole lot more happening behind the scenes to give you the results you need. Google on Monday launched a video that explains the science behind how the massive search engine actually works.

Matt Cutts, software engineer head of Google’s webspam team, details in a YouTube video how the search engine giant thoroughly scours the web on a daily basis to provide the most up-to-date results to users.
“There are three things you need to do to be the best search engine in the world. First, you need to crawl the web comprehensively and deeply, then you want to rank or serve those pages and return the most relevant ones first,” Cutts said. Although Google crawls the web on a daily basis, that wasn’t always the case.

But this method wasn’t optimized since a lot of the information would be out of date. In 2003, Google switched to crawling a significant amount of the Internet each day. By scouring the web each day for new content, it incrementally updated its index.