A channel is the route that is used by a network to send and receive data from the access point to the device
In more technical terms, a channel is the frequency range that a wireless access point uses to transmit data to a client device. As you may know, there are two frequency bands used in WiFi; the 2.4ghz band and the 5ghz band. Within these bands are smaller frequency bands that are called channels.
Within this band there are 14 different channels to choose from which range from 1-14. But, the only channels that you should use are 1, 6, and 11, because these channels are non-overlapping channels, or channels that will not interfere with each other. So, when planning for a 2.4ghz wireless network, there are really only 3 channels to choose from.
Too many networks using the same channels may cause problems.
For this frequency band, there are 25 non-overlapping channels to choose from which range from 36-165. The difference here is that each channel is 4 numbers apart. So, after channel 36, the next channel is 40 and so on.