Users generate data as they interact with apps. Apps frequently require access or save this data to function properly and provide the best possible user experience. These include personal settings, media, and other documents. It can be used to track clicks, purchases of products and other conversions within the application. There are many ways to gather this information, including asking the user to provide it, determining it based on their behavior on the web or buying it from a third party. Ideal customer data should be centrally stored and in a standardised format that allows for easy integration and exchange between applications. There are emerging standards for the profile of customer data by industry sector that can aid in defining the data models to be used.
There are numerous methods for storing data and the storage system used in an app will influence how the user interface presented. The most commonly used is the storage of files, in which the data is saved as folders and files that are arranged in an order. Hard disk drives and cloud storage such as Google Drive or Microsoft OneDrive use this approach. Block storage is another option, where data is divided into blocks and stored in any storage infrastructure. They are identified by identifiers to make them easy to locate and act upon.
Early systems included tools which provided detailed information about the properties and characteristics of storage media in textual format. Modern systems, like Android provide visualisations of these functions, such as capacity/usage and life span. Capacity/usage visualisations are generally horizontally stacked bar charts. Lifespan is usually displayed as a circular pie graph or variants like doughnut charts.