A firehose API is a real-time data streaming service that continuously transmits all available data from a source to multiple subscribers, allowing them to visualize, publish, or graph the data instantly as it updates. One prominent example is the Twitter firehose API, which delivers 100% of tweets in real time, showcasing the significant volume such APIs can handle, although access to it is restricted to a few companies. Besides Twitter, data firehoses can be formed from various data sources, such as weather updates, stock prices, and Internet of Things sensors. These APIs can be syndicated, enabling the distribution of the main data stream into smaller streams for specific subscribers. The process of syndicating and consuming a firehose API can be demonstrated through applications and demos, which illustrate the practical uses of real-time data streams.