Using \"An\" and \"A\" in a sentence [duplicate]

Using \"An\" and \"A\" in a sentence [duplicate] References This question already has an answer here: When should I use “a” versus “an” in front of a word beginning with the letter h? 9 answers I\'m trying to understand this simple concept. As far as I understood it, back to the days when I was a student, \"an\" should be used only before vowel words, that is, only before the following words: \"a\",\"i\",\"o\",\"u\". Yesterday my sister asked me a question related to this subject and I wasn\'t sure if my answer was correct because there are so much controversial sources explaining this subject. The original question she asked me was which one of the following is the correct form to be used in a sentence: An history Or A history I told her that she should use \"a history\" only because \'h\' isn\'t a vowel word. Is it correct? Thank you very much