An automated personal assistant or an Intelligent Personal Assistant is a mobile software agent that can perform tasks, or services, on behalf of an individual based on a combination of user input, location awareness, and the ability to access information from a variety of online sources (such as weather conditions, traffic congestion, news, stock prices, user schedules, retail prices, etc.).

There are two types of automated personal assistants: intelligent automated assistants (for example, Apple’s Siri and Tronton’s Cluzee), which perform concierge-type tasks (e.g., making dinner reservations, purchasing event tickets, making travel arrangements) or provide information based on voice input or commands; and smart personal agents, which automatically perform management or data-handling tasks based on online information and events often without user initiation or interaction.

According to Chi-Hua Chien of Kleiner Perkins Caufield & Byers, examples of tasks that may be performed by a smart personal agent-type of automated personal assistant include schedule management (e.g., sending an alert to a dinner date that a user is running late due to traffic conditions, update schedules for both parties, and change the restaurant reservation time) and personal health management (e.g., monitoring caloric intake, heart rate and exercise regimen, then making recommendations for healthy choices).

Both types of automated personal assistant technology are enabled by the combination of mobile computing devices, application programming interfaces (APIs), and the proliferation of mobile apps. However, intelligent automated assistants are designed to perform specific, one-off tasks specified by user voice instructions, while smart personal agents perform ongoing tasks (e.g., schedule management) autonomously.

Source: Wikipedia