Personal digital assistants (PDAs) are data-centric devices designed for on-the-move computing and communications. PDAS are a complete contact database with storage for phone, address and email details, calendar and appointment scheduling, memos and to do lists. They are also mobile computing devices for office functions such as reading and editing word documents, spread sheets, PDFs and other files. In addition to data applications, some models are appearing that include phone functionality, such as voice-activated phone dialing, messaging and global roaming.

PDAs come in a range of shapes and sizes from low-end models that can be used in place of a paper diary to high-end models that are intended for global mobile computing and connectivity with a suite of business applications. There's almost a model for every application and, if manufacturers have their way, we'll all by discarding our humble diaries in place of these digital devices.