[LAU] Clics and pops

Hello, you may recognize my name : i'm one of the linuxaudio users who yelled about watchdog timeout (jack problem). it still doesn't work and i'm still interested in any advice... BUT my mail isn't about that problem. I couldn't record and playback simultaneously so i tried another solution : recording through my Micro BR and then use ardour to playback and mix the audio files. The only problem that remains is i have clics or pops (i dont know the difference) on my guitar record...i tried to suppress them with audacity, but it seems not to work (with me as a user). Could i have explanations about using that function? Is there a more efficient/ easier tool to do that? why do clics and pops exist (it's a wav file)?