Broadband is a type of high speed data transmission that can carry large amounts of data at once. This can be through a single wire or cable, but also wirelessly. Broadband is often mentioned in relation to internet access via high-speed networks. Examples include cable, DSL, Wi-Fi, WiMAX, 3G, 4G, FiOS, and satellite. Typically, these are much faster than data transmissions using dial-up access.
To understand the difference, consider an analogy using a car and a skateboard. With broadband access, you’re in a car – perhaps even a bus- and you can travel faster and carry more people than someone riding a skateboard. The skateboarder can move one person around faster than walking, but not nearly as fast as a car.
Besides speed, broadband has another advantage over dial-up: it doesn’t use a phone line. Dial-up access connects to the Internet via a modem and a telephone line. Since the line is used constantly while the dial-up connection is being used, phones connected to that line cannot be used to make or receive calls. Though broadband may require its own cable, it will never need to use a telephone line. For people with landline phones, this makes it especially appealing.
Since its introduction in the early 2000’s, broadband has not only replaced dial-up (BT stopped supporting dial-up in 2013), but continues to improve its own strength. For example, in 2005 broadband speeds averaged 2Mbps. This led to the creation of YouTube, whose video streaming was not even a possibility in the early days of broadband, let alone dial up. Nine years later, and the average broadband speed in the UK was 18.7mbps. In 2012, the UK’s first 4G network was launched. This installation was created with the goal of providing people with mobile devices with broadband connection speeds over mobile networks.
The advent of broadband services is what allowed video streaming to become mainstream into virtually every home in the UK. The Government’s superfast broadband program is still working to deliver the highest possible connections speeds to everyone in the UK.
Wikipedia offers further detail here.