WLAN has a major advantage compared to wired communication: You can use your laptop, iphone or android everywhere and don't have to struggle with a cable. Just comare it with wireless and wired phones. There are some disadvantages: WLAN has usually a lower throughput than wired connection. But that's acceptable for normal browsing, eMail processing and chatting. Unfortunately there is another disadvantage: The number of WLAN channels to communicate with the accesspoint is limited. If a neighbour uses the same channel or a channel nearby the throughput of WLAN will decrease significantly.

 There exist 11 (USA) and 13 (Deutschland) channels on the 2.4 GHz Band and 19 Kanäle on the 5 GHz Band. Most of the current WLAN cards can use the 2.4 GHz band only.  The 5 GHz band is new and not pervasie and the cards are more expensive. Don't think now 13 accesspoints can communicate on different channels without any throtteling interferences. Channels interfere if their frequency distance is too small. This means channels have to have a distance of at least  5. Therefore you find the suggestion to use channels 1,6 and 11 only.