Why is TV cable faster than Internet cable?

On our TV, I can go channel to channel quickly, even through the HD channels quickly, but streaming video on the cable internet is incredibly slower to do in comparison. . Both services work through the same type of cable coax line. Could somebody mind explaining?

Simple answer: bandwidth. A cable is capable of carrying many frequencies of signal, but only a small range of frequencies is given over to internet traffic, while the rest is used for television and telephony. Certain frequency ranges in the spectrum the cable carries are divided up into 6MHz channels, each channel capable of carrying 38Mbps, and multiplexed to carry anything up to 12 standard definition stations (fewer in HDTV, of course).

So why don't they just give over one of these channels for internet and give everyone a 38Mbps connection? The difference is that everyone gets the same signal with television channels: the same data is broadcast to every subscriber from one central location (the headend), and the cable decoder box selects and decodes the channel the viewer chooses, ignoring the other frequencies (and the other channels multiplexed on the same frequency). But with the internet, every user wants different data, so broadcasting like that is impossible (besides, internet traffic is two-way). Instead a range of frequencies is given over to internet traffic and each user's cable modem negotiates its little slice of bandwidth. Add to that the fact that instead of being a simple route from headend to user, data on the internet has to negotiate multiple networks sprawling across the globe, and the information, instead of being a single stream, is divided up into packets. Each packet may end up going along a different route to the last; it might take longer to arrive, it might get lost and have to be retransmitted, the packets may not arrive in the order they were sent. With cable TV, data is sent continuously regardless of how many people are "demanding" it - the signal is the same if ten people are watching a station or if ten million are watching. On the internet, data gets sent to *every* user on demand (leading to big problems with high demand, like a much anticipated film trailer, for example - the server hosting the video gets swamped with demands for data).

In short: cable TV is fast because its bandwidth is higher and everyone gets the same data; cable internet is slow because the bandwidth is smaller and everyone wants different data.