People might be thinking about this as how a search engine works for the optimization of a website, to increase its rank, and set the indexes of websites to come in series with the related content a user wants to see. Actually, Google uses a crawler for collecting the data and the information required for a particular query in whole content found on the internet. The crawlers bring all the information and give this to the search engine for creating an index.
The index than furthermore uses the algorithm to match the data according to the query and gives the output resulted in the index according to the ranks of content available on site.
A site without content is not fully optimized and functioning properly. And for SEO the content should contain specific variables and key functioning.