Difference between Can and May

Key Difference: The word 'can' is generally used to denote ability. On the other hand, the word 'may' refer to denote permissions in a polite and formal manner. However, the word 'can' is also used to ask for permissions but in an informal manner.

Can and may, often create confusion. Thus, it is very important to determine the actual differences between the two. Can is generally associated with the capability. For example- ‘He can do that task'. In this sentence, a person is being considered to be capable of performing a task. On the other hand, may is generally related with the act of seeking a permission. For example- ‘May I take a break’.

Sometimes, can is also used to seek permission. However, it is an informal way to seek permission. Thus, in environments like that of offices, a person tends to use may rather than can, as can is less formal. May is also used sometimes to suggest the possiblity of something. For example - he may come today.

According to Dictionary.com, can is described as -

to be able to; have the ability, power, or skill to: She can solve the problem easily, I'm sure.
to know how to: He can play chess, although he's not particularly good at it.
to have the power or means to: A dictator can impose his will on the people.
to have the right or qualifications to: He can change whatever he wishes in the script.
may; have permission to: Can I speak to you for a moment?

And May is described as –

(used to express possibility): It may rain.
(used to express opportunity or permission): You may enter.
(used to express contingency, especially in clauses indicating condition, concession, purpose, result, etc.): I may be wrong but I think you would be wise to go. Times may change but human nature stays the same.
(used to express wish or prayer): May you live to an old age.
Archaic. (used to express ability or power.)

Comparison between Can and May:

	Can	May
Definition	Can is generally associated with the capability.	May is generally related to ask for permissions.
type	Casual term in context to permission	Formal term in context to permission
Examples	I do not think I can lift that object. I can solve this equation. Can I go to meet my parents?	May I come in? You may visit me next Sunday. You may ride my horse.
Origin (Online Etymology Defintion)	From Old English 1st & 3rd person singular present indicative of cunnan "know, have power to, be able," (also "to have carnal knowledge"), from Proto-Germanic *kunnan "to be mentally able, to have learned" (cf. Old Norse kenna "to know, make known," Old Frisian kanna "to recognize, admit," German kennen "to know," Gothic kannjan "to make known").	Old English mæg "am able" (infinitive magan, past tense meahte, mihte), from Proto-Germanic root mag-, infinitive maganan (Old Frisian mei/muga/machte "have power, may;" Old Saxon mag/mugan/mahte; Middle Dutch mach/moghen/mohte; Dutch mag/mogen/mocht; Old High German mag/magan/mahta; German mag/mögen/mochte; Old Norse ma/mega/matte; Gothic mag/magan/mahte "to be able").