Upd

Author: mprinc

site/learn/Introduction.md

@@ -7,11 +7,11 @@ permalink: /learn/
 next: /learn/queries/
 ---
 
-> Learn about GraphQL, how it works, and how to use it in this series of articles. Looking for documentation on how to build a GraphQL service? There are libraries to help you implement GraphQL in [many different languages](/code/). For an in-depth learning experience with practical tutorials, visit the [How to GraphQL](https://www.howtographql.com) fullstack tutorial website. We have also partnered with edX to create a free online course, [Exploring GraphQL: A Query Language for APIs](https://www.edx.org/course/exploring-graphql-a-query-language-for-apis).
+> Learn about GraphQL, how it works, and how to use it in this series of articles. Looking for documentation on how to build a GraphQL service? There are <span class='definition'>libraries</span> to help you implement GraphQL in [many different languages](/code/). For an in-depth learning experience with practical tutorials, visit the [How to GraphQL](https://www.howtographql.com) <span class='important'>fullstack tutorial website</span>. We have also partnered with edX to create <span class='definition'>a free online course</span>, [Exploring GraphQL: A Query Language for APIs](https://www.edx.org/course/exploring-graphql-a-query-language-for-apis).
 
-GraphQL is a query language for your API, and a server-side runtime for executing queries by using a type system you define for your data. GraphQL isn't tied to any specific database or storage engine and is instead backed by your existing code and data.
+GraphQL is <span class='definition'>a query language for your API</span>, and a <span class='definition'>server-side runtime for executing queries</span> by using a type system you define for your data. GraphQL isn't tied to any specific database or storage engine and is instead backed by your existing code and data.
 
-A GraphQL service is created by defining types and fields on those types, then providing functions for each field on each type. For example, a GraphQL service that tells us who the logged in user is (`me`) as well as that user's name might look something like this:
+A <span class='definition'>GraphQL service</span> is created by defining types and fields on those types, then providing functions for each field on each type. For example, a GraphQL service that tells us who the logged in user is (`me`) as well as that user's name might look something like this:
 
 ```graphql
 type Query {
@@ -36,7 +36,7 @@ function User_name(user) {
 }
 ```
 
-Once a GraphQL service is running (typically at a URL on a web service), it can receive GraphQL queries to validate and execute. A received query is first checked to ensure it only refers to the types and fields defined, then runs the provided functions to produce a result.
+Once a GraphQL service is running (typically at a URL on a web service), it can receive GraphQL queries to <span class='definition'>validate</span> and execute. A received query is first <span class='important'>checked</span> to ensure it only refers to the types and fields defined, then runs the provided functions to produce a result.
 
 For example the query: