This document discusses the importance of metadata from a search engine perspective. It outlines how search engines have evolved to make use of metadata over time, from directly extracting metadata to enhance search results, to being able to search metadata directly and provide direct answers to queries. The document also notes that metadata adoption on the web has increased over time, with around 31% of webpages and 5% of domains now containing some metadata, primarily in the form of RDFa. Metadata allows search engines to better understand and organize content to provide more relevant search results.