What is background and foreground?

A priority assigned to programs running in a multitasking environment. The foreground contains the applications the user is working on, and the background contains the applications that are behind the scenes , such as certain operating system functions, printing a document or accessing the network.

Foreground services perform operations that are noticeable to the user . Foreground services show a status bar notification, so that users are actively aware that your app is performing a task in the foreground and is consuming system resources.

Foreground refers to the active apps which consume data and are currently running on the mobile. Background refers to the data used when the app is doing some activity in the background, which is not active right now.

Foreground services are an advanced Android concept which allows you to display notifications to your users when running long lived background tasks . The notification acts like any other notification, however it cannot be removed by the user and lives for the duration of the service.