Android is a mobile operating system developed by Google, based on the Linux kernel and designed primarily for touchscreen mobile devices such as smartphones and tablets.

Android's user interface is mainly based on direct manipulation, using touch gestures that loosely correspond to real-world actions, such as swiping, tapping and pinching, to manipulate on-screen objects, along with a virtual keyboard for text input.

In addition to touchscreen devices, Google has further developed Android TV for televisions, Android Auto for cars, and Android Wear for wrist watches, each with a specialized user interface.

Variants of Android are also used on notebooks, game consoles, digital cameras, and other electronics.

With the application of probability sampling in the 1930s, surveys became a standard tool for empirical research in social sciences, marketing, and official statistics.

The methods involved in survey data collection are any of a number of ways in which data can be collected for a statistical survey.

These are methods that are used to collect information from a sample of individuals in a systematic way.

First there was the change from traditional paper-and-pencil interviewing (PAPI) to computer-assisted interviewing (CAI).

Now, face-to-face surveys (CAPI), telephone surveys (CATI), and mail surveys (CASI, CSAQ) are increasingly replaced by web surveys.

A personal digital assistant (PDA), also known as a handheld PC, or personal data assistant, is a mobile device that functions as a personal information manager.

The term evolved from Personal Desktop Assistant, a software term for an application that prompts or prods the user of a computer with suggestions or provides quick reference to contacts and other lists.

PDAs were largely discontinued in the early 2010s after the widespread adoption of highly capable smartphones, in particular those based on iOS and Android.

A mobile application software or mobile app is an application software designed to run on mobile devices such as smartphones and tablet computers.

Most such devices are sold with several apps bundled as pre-installed software, such as a web browser, email client, calendar, mapping program, and an app for buying music or other media or more apps.

Some pre-installed apps can be removed by an ordinary uninstall process, thus leaving more storage space for desired ones.

Where the software does not allow this, some devices can be rooted to eliminate the undesired apps.

A tablet computer, commonly shortened to tablet, is a thin, flat mobile computer with a touch screen display, which is usually in color, processing circuitry, and a rechargeable battery in a single device.

Tablets often come equipped with sensors, including digital cameras, a microphone, and an accelerometer so images on screens are always displayed upright.

The touchscreen display uses the recognition of finger or stylus gestures to replace the mouse, trackpad and keyboard used in laptops.