Networks with higher bandwidth are able to transfer a greater number of data packets than those with a low bandwidth. It's best to think of data transfer as water flowing through a hosepipe - there's only so much water that can fit inside the pipe at any given moment, with larger capacity pipes being able to carry more.
While bandwidth has no bearing on the speed at which data packets travel from one node to another, a low capacity can create a bottleneck in a network that will result in slow or unresponsive applications for the end user.
For example, low bandwidth might speedily display a basic web page that just consists of text, but would struggle to carry enough large data packets at once to support an online video game. That leads to issues like lag, where the interrnet speed is too slow to show what is happening in real-time, or causing a streamed movie to stall.

Things that can affect bandwidth include

• number of users on the network,
• types of traffic on the network (big multimedia files will slow down a network), and
• availability of routers and access points.