The application development documents provide reference for you to develop applications using the APIs provided by OpenHarmony. The documents provided walk you through how to use JavaScript \(JS\) APIs to develop applications on the standard system.
To get a glimpse of the basic methods for developing applications, see [Basics](quick-start/Readme-EN.md). For details about the API list and references, see [Reference](reference/Readme-EN.md).
To get a glimpse of the basic methods for developing applications, see [Basics](quick-start/start-overview.md). For details about the API list and references, see [Reference](reference/apis/js-apis-featureAbility.md).
To better understand frequently used modules, see the development guidelines for [UI](ui/Readme-EN.md), [Media](media/Readme-EN.md), and [Connectivity](connectivity/Readme-EN.md).
To better understand frequently used modules, see the development guidelines for [Ability](ability/ability-brief.md), [UI](ui/arkui-overview.md), and [Media](media/audio-overview.md).
For details about the principles and basic information of each subsystem, see the README file in **docs/en/readme**.