Bandwidth commonly describes the capacity available to carry data over a connection or link. A home internet package may advertise a maximum rate, while an individual streaming device can face a lower practical limit through Wi-Fi, congestion or another bottleneck. Stable delivery to the actual source matters as well as the connection's headline capacity.
A practical example
A household connection can have enough overall capacity for several tasks while a television in a distant room receives data poorly over Wi-Fi. Improving the local link may help more than purchasing a faster package that leaves the same weak wireless path unchanged.
A common misunderstanding
Do not confuse network capacity with media bitrate or actual throughput. They describe related but different quantities, and a single advertised number cannot identify every bottleneck in the viewing path.
Related terms
Stable technical definition. Editorial approach