Concordances list words in the Bible and the passages in which they appear. Some concordances list every word in the Bible; other concordances list only the most significant words. Concordances are meant to be used with a specific version of the Bible. If you look up a word in a concordance for a version of the Bible that is different from the one that you are using, you may not see the passage that the word you chose came from; that version of the Bible may use a different word in your passage.
John 3:16 by Kevin Gardner
Nelson's Complete Concordance of the New American Bible by 
The NRSV Concordance Unabridged : Including the Apocryphal/Deuterocanonical Books by 
Reader's Digest Family Guide to the Bible : A Concordance and Reference Companion to the King James Version by 
Complete Concordance to the Bible (Douay Version) by