text: As in the case of single molecule fluorescence spectroscopy, the technique known as single channel recording can be used to obtain specific kinetic information—in this case about ion channel function—that is not available when ensemble recording, such as whole-cell recording, is performed.  Specifically, ion channels alternate between conducting and non-conducting classes, which differ in conformation.  Therefore, the functional state of ion channels can be directly measured with sufficiently sensitive electronics, provided that proper precautions are taken to minimize noise.  In turn, each of these classes may be divided into one or more kinetic states with direct bearing on the underlying function of the ion channel. Performing these types of single molecule studies under systematically varying conditions (e.g. agonist concentration and structure, permeant ion and/or channel blocker, mutations in the ion channel amino acids), can provide information regarding the interconversion of various kinetic states of the ion channel.  In a minimal model for an ion channel, there are two states: open and closed.  However, other states are often needed in order to accurately represent the data, including multiple closed states as well as inactive and/or desensitized states, which are non-conducting states that can occur even in the presence of stimulus.