The noun ‘use’ comes from the verb ‘use’, meaning to employ for a given purpose or put into action. Examples : ‘I use a keyboard to type in words.' ‘I use a knife and fork to eat my dinner’. ‘I use short words in speaking with small children, because they probably won’t understand long words’. As a noun, ‘use’ means a given purpose or application. Examples : ‘The English language is in common use around the world’ , ‘I put my keyboard to good use’. For the noun ‘usage’ the basic dictionary definition can look pretty much the same as that for ‘use’, but with ‘usage’ there is a sense of ‘continued’ or ‘common’ use. The difference is that ‘usage’ is the way the language is actually used, as distinct from what might look correct if you try to construct a sentence or phrase from a dictionary and grammar book. Examples: ‘Although old-fashioned grammarians say you should never split an infinitive, that is done every day in common usage.’ ‘I was taught at school that every sentence must have a verb, but actual usage shows that many excellent writers include in their work ’sentences’ without verbs.

there are really three words: to use (verb as in "I use my credit card") use (noun as in "What use is paper money?" or "that word is no longer in use" or "it has fallen out of use" ) usage (noun as in "the usages of the last 50 years") Use and usage are almost always interchangable. "Use" is the more common, conversational choice. "Usage" implies a more scholarly or learned point of view. The dictionary disagrees and says "usage" is the act, manner or amount of "using"