In 1890, James Strong published his work of 35 years that listed each each unique word in the Old Testament (Hebrew) and New Testament (Greek). This is often used as a powerful tool for doing research on the actual context of a passage in the Bible. It is still used today and is the most widely used concordance and dictionary of Bible words from the King James Version of the Bible.

Such a tool is especially useful with the English translations are unclear. A quick example of such a place is John 21:16. The passage follows from the King James Version with Strong's numbers in parentheses.

16. He saith (3004) to him (846) again (3825) the second time, (1208) Simon (4613), {son} of Jonas (2495), lovest thou (25) me? (3165) He saith (3004) unto him, (846) Yea, (3483) Lord; (2962) though (4771) knowest (1492) that (3754) I love (5368) thee. (4571) He saith (3004) unto him, (846) Feed (4165) my (3450) sheep. (4263)

A quick glance will show that 'love' in the above passage is two different words. Jesus used the word 'agapao' which is a form of 'agape', while he was answered back using 'phileo' which is is a form of 'philia' or 'philos'. More about this can be read at Greek words for love. Much of this essence of this dialogue is lost in translation. A concordance, such as Strong's, sheds light upon much of the actual meaning of words used.