React components
Gatsby uses React underneath, so it can take advantage of all that React has to offer. A React component is mostly a JavaScript function that returns something. By leveraging GraphQL, the developer can use Gatsby's source plugin to pass data into the page. Properties are usually sent into the component and then events are passed up. These patterns – props down, events up or data down, and actions up, are used in several JavaScript frameworks and are very easy to understand. Once a React component is created, it may be imported to another component for easy reuse.
Tag convention
As mentioned in the previous section, once a component is created, it can be invoked or used in Gatsby as if it was its own HTML tag, so its use is familiar to those who are familiar with working with HTML tags. This is useful for readability, since the output looks like HTML and not JavaScript code. The convention for working with React components is to encapsulate the name...