Final answer:
A web service that enables users to broadcast short messages is known as a microblogging platform, such as Tw-itter. It allows for rapid and wide dissemination of information but differs from social networking sites, podcasting services, and instant messaging applications.
Step-by-step explanation:
The web service that enables users to broadcast short messages is commonly known as a microblogging platform. This medium allows for quick and concise sharing of information, which can be disseminated widely and rapidly among users. Microblogging platforms form a part of the diverse range of social media available on the Internet, including services like Twi-tter and China's Sina Weibo. These platforms differ from social networking sites like Face-book, which are generally used for more personal and in-depth interactions.
Microblogging is also distinct from podcasting services, which are for creating and distributing serial audio or video content, and from instant messaging applications that facilitate private, real-time text conversations. The unique feature of microblogging platforms is their focus on brief, public posts that can virally spread through user networks. These platforms have had significant impact on social interaction, global communication, and even political processes by providing a space for rapid information sharing and public discourse.