Why there are only 13 channels in WLAN802.11b(WiFi)?

Why there are only 13 channels in WLAN802.11b(WiFi) although frequency range is 2.40-2.4835GHz, Bw is 22MHz with 5GHz spacing?

channels overlap in 80211b/g. there are only 3 non overlapping channels. channel 1, 6, 11.

yes. BW is same, but channels in 5GHz don't overlap.

but why they dont overlap?

the channels are orthogonal. you'll get less interference. what do you think? sounds good! why should they overlap? it's better they don't.

ok, I understand, if they are orthogonal then interference will be less

so i helped you. thanks.