In the linux kernel we have libraries and android runtime that helps to work with different concepts.
For example SqlLite is a library to store data within the App. We can have media libraries to interact with Videos, Audios and Pictures etc. We also have a very important library called as WEBKIT.
What is WEBKIT in Android?Webkit is an browser engine powering safari, Google Chrome and Android Internet browser.
Android Runtime is a component which takes care of the core services like Google MAP, Location Service and also provides a runtime for running our apps on Google's Android Operating System.
Android gives every required functions to a App like Memory Management, Device Mangment and other jobs which are the application requisition. Its the runtime's responsibility to interact with whom the App requiring.
The runtime environment actually targets different architectures which exist on different phones. The runtime is able to understand and push the native code according to Architecture of the phone.