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pages/docs/reference/extensions/index.md

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 ## What's an extension?
 
-Extension is a mechanism in AsyncAPI that enables you to add custom fields to AsyncAPI document. You can define your own extensions, use them only for your use case inside your company. You can also share your extensions with others. This way an extension that is adopted by others can one day become core part of AsyncAPI specification.
+Extension is a mechanism in AsyncAPI that enables you to add custom fields to an AsyncAPI document. You can define your own extensions or use them only for your use case inside your company. You can also share your extensions with others. This way an extension that is adopted by others can one day become a core part of the AsyncAPI specification.
 
 ## Usage in an AsyncAPI document
 AsyncAPI extensions are those that are preceded by `x-`, for example `x-linkedin`. They can be placed in the AsyncAPI document in locations specified by documentation of given extension.