The Adobe AIR runtime may be a relatively new platform, but it actually embeds three highly mature and stable cross-platform technologies to power AIR applications. These are the following:

• WebKit: Used for rendering HTML content inside an AIR app. WebKit is an open source, cross-platform browser and is the underlying rendering engine on which Apple’s Safari browser is built. WebKit is known for its strong support of W3C standards, such as HTML, XHTML, Document Object Model (DOM), Cascading Style Sheets (CSS), and ECMAScript. However, it also provides support for enhanced func- tionality — enabling the creation of cool stuff such as rounded corners using CSS. Because you’re developing solely for WebKit and not for every browser under the sun, you’re free to take advantage of these nonstan- dard extensions. For more info on WebKit, go to www.webkit.org.
• Adobe Flash Player: Used for playing Flash media (SWF files). Flash Player is a cross-platform virtual machine used to run media created in the Adobe Flash authoring environment and full SWF-based applications created using Adobe Flex. Flash Player has an embedded JavaScript-like scripting language called ActionScript 3. Inside your app, you can access existing Flash Player API calls as well as some enhanced functionality for vector-based drawing, multimedia sup- port , and a full networking stack.
• SQLite: A database engine for enabling local database access. It’s an extremely lightweight, open source, cross-platform SQL database engine that is embedded in many desktop and mobile products. In contrast to most SQL databases, it doesn’t require a separate server process, and it uses a standard file to store an entire database (tables, indexes, and so on). For more info on SQLite, go to www.sqlite.org.

This Figure shows an overview of the AIR runtime architecture: Source: Adobe AIR for Dummies