Editing Shall and will (section)

===Independent uses===
The main use of ''should'' in modern English is as a synonym of ''[[ought to]]'', expressing quasi-obligation, appropriateness, or expectation (it cannot be replaced by ''would'' in these meanings). Examples:
* You should not say such things. (it is wrong to do so)
* He should move his pawn. (it is optimal to do so) 
* Why should you suspect me? (for what reason is it proper to suspect me?)
* You should have enough time to finish the work. (a prediction)
* I should be able to come. (a prediction, implies some uncertainty)
* There should be some cheese in the kitchen. (expectation)

Other specific uses of ''should'' involve the expression of [[irrealis mood]]:
* in condition clauses ([[protasis]]), e.g., "If it should rain" or "Should it rain"; see [[English conditional sentences]]
* as an alternative to the subjunctive, e.g., "It is important that he (should) leave"; see [[English subjunctive]]

The main use of ''would'' is in conditional clauses (described in detail in the article on [[English conditional sentences]]):
*I would not be here if you hadn't summoned me.
In this use, ''would'' is sometimes (though rarely) replaced by ''should'' when the subject is in the first person (by virtue of the same prescriptive rule that demands ''shall'' rather than ''will'' as the normal future marker for that person). This ''should'' is found in stock phrases such as "I should think" and "I should expect". However its use in more general cases is old-fashioned or highly formal, and can give rise to ambiguity with the more common use of ''should'' to mean ''ought to''. This is illustrated by the following sentences:  
* You would apologize if you saw him. (pure conditional, stating what would happen)
* You should apologize if you see him. (states what would be proper)
* I would apologize if I saw him. (pure conditional)
* I should apologize if I saw him. (possibly a formal variant of the above, but may be understood to be stating what is proper)

In archaic usage ''would'' has been used to indicate present time desire. "Would that I were dead" means "I wish I were dead". "I would fain" means "I would gladly".

More details of the usage of ''should'', ''would'' and other related auxiliaries can be found in the article on [[English modal verbs]].