Using image in Gatsby application by a clear way

Gatsby has many features to win the developers' love and prevails over other mainstream static site generators. Image display is a common task in web development, how to use it is confused, this article described the answer to it. The official doc about working with image in Markdown told us the placing the featuredImage in the same position of markdown file: 'Kyle-mathews.jpeg' Gatsy-image query(graphql) using relative path under the path defined in gatsby-source-filesystem as query condition!