The words afterward and afterwards are both used correctly. The only significant limitation is that when the word afterwards is used, it can only be used as an adverb and in relation to time. For example: "The boy needs to eat all of his dinner and he can have dessert afterwards." It is considered more formal to use the word afterward without the "s" at the end. Also if a person is describing
. the order of objects and not a specific time, the word afterward is the only acceptable word to use.One thing to remember is that if a person is unsure about usage of the word afterward as opposed to the word afterwards in a sentence, the best thing is to refrain from using the s at the end of the word, and the writer is always going to write the word in a correct manner. Therefore, when in doubt, do not include the letter s. Other words similar to these words can also be directional and include: toward and towards, forward and forwards, backward and backwards as well as upward and upwards.The antonym of afterward or afterwards is beforehand, but beforehand never includes an s at the end of the word.Another useful thing to remember about certain words that are written with and without the letter s is that words with the letter s at the end are often nothing more than the British spellings of the words. For instance, the word towards is the common spelling of persons who live in Great Britain, whereas the word toward is the common spelling of persons who live in the United States of America. Similarly, the word afterwards is most typically used by British individuals and afterward is the word of choice for Americans. Both spellings of towards, toward, afterwards and afterward are correct, but it is best for writers to use the version that applies to the audience for which the words are written.More reference links: http://english.stackexchange.com/questions/6639/afterward-versus-afterwards-which-and-or-when http://languagetips.wordpress.com/2009/11/05/language-tips-afterward-or-afterwards-discrete-or-discreet/