an vs the

an

article
  • Used before one and words with initial u, eu. 

  • Used before a vowel sound. 

  • Used before all consonants. 

  • Used before /h/ in an unstressed syllable. 

  • Used before /h/ in a stressed syllable. 

prep
  • In each; to or for each; per. 

noun
  • The first letter of the Georgian alphabet, ა (Mkhedruli), Ⴀ (Asomtavruli) or ⴀ (Nuskhuri). 

num
  • one 

the

prep
  • For each; per. 

article
  • Introducing a singular term to be taken generically: preceding a name of something standing for a whole class. 

  • Used before an adjective, indicating all things (especially persons) described by that adjective. 

  • Used to indicate a certain example of (a noun) which is usually of most concern or most common or familiar. 

  • Added to a superlative or an ordinal number to make it into a substantive. 

  • Used before a body part (especially of someone previously mentioned), as an alternative to a possessive pronoun. 

  • When stressed, indicates that it describes an object which is considered to be best or exclusively worthy of attention. 

  • Definite grammatical article that implies necessarily that an entity it hints at is presupposed; something already mentioned, or completely specified later in that same sentence, or assumed already completely specified. 

  • Used before an object considered to be unique, or of which there is only one at a time. 

  • Used before a noun modified by a restrictive relative clause, indicating that the noun refers to a single referent defined by the relative clause. 

  • Used before a superlative or an ordinal number modifying a noun, to indicate that the noun refers to a single item. 

adv
  • With a comparative or with more and a verb phrase, establishes a correlation with one or more other such comparatives. 

  • With a comparative, and often with for it, indicates a result more like said comparative. This can be negated with none. 

How often have the words an and the occurred in a corpus of books? (source: Google Ngram Viewer )