Left hand techniques start from the simple pressing down on the string (mostly with the thumb between the flesh and nail, and the ring finger), sliding up or down to the next note ("shang" 〈上〉 and "xia" 〈下〉), to vibrati by swaying the hand ("yin" 〈吟〉 and "nao" 〈猱〉, there are as many as 15 plus different forms of vibrato), plucking the string with the thumb whilst the ring finger stops the string at the lower position ("qiaqi" 〈掐起 / 搯起〉), hammering on a string using the thumb ("yan" 〈掩 / 罨〉), to more difficult techniques such as pressing on several strings at the same time.