What application is required to access the Internet from a smartphone?

To access the Internet from a smartphone, the most suitable application is a web browser. A web browser is specifically designed to retrieve, present, and navigate information on the web, allowing users to visit websites, access online services, and view content. Web browsers play a crucial role in the functionality of smartphones by providing a user-friendly interface to interact with the Internet.

While a microbrowser is a type of web browser that is optimized for mobile devices, the term is not as commonly used in contemporary technology discussions and may not encompass the full capability of modern web browsers found on smartphones. Therefore, while it does facilitate Internet access, it is not the universal or primary application that most users would utilize today.

A synchronization program is not related to Internet access; it's typically used to keep data in agreement between devices, ensuring that files, contacts, and calendars are consistent across platforms.

A software application could refer to many types of applications, but it does not specifically address the application needed for Internet access, making the web browser the most accurate choice for this question.