'Bandwidth' in web development and networking is the data transfer rate across a specific path. It's the capacity of a web connection to transport a maximum quantity of data from one point to another in a set time frame, usually measured in bits per second (bps).

Bandwidth significantly influences the speed and efficiency of data transmission over the internet. Higher bandwidth means faster data transfer, resulting in quicker loading of web pages and online content. It is crucial for user experience, especially on content-rich websites, streaming services, and in online gaming.

Web developers need to factor in bandwidth while designing and optimizing websites and applications. This includes optimizing media files, minifying code files, and using caching and CDNs to reduce data transfer and improve load times, especially for users with varying bandwidth speeds.

With increasing internet usage and more data-heavy applications, the demand for higher bandwidth is growing, leading to advancements in internet infrastructure like fiber-optic transmission and 5G networks.

To conclude, bandwidth is a fundamental element of internet infrastructure, affecting web application performance and user experience. Effective bandwidth management and optimization are crucial for delivering fast and responsive online services.