Can - Used to denote the ability of the subject to perform an action or to request permission to perform an action
Could - Used to denote the ability of the subject to perform an action or an offer made by the subject to perform an action
May - Used to denote the probability of an action taking place or to request permission to perform an action
Might - Used to denote the probability of an action taking place or to make suggestions
Will - Used to denote the surety of an action taking place or the assurance of the subject to perform a particular action