Concordances are one of the most basic tools of Bible study. A concordance is an alphabetical listing of the words used in the Bible, giving the scripture reference and part of the verse for the context.
Using a concordance, one can find the location of a Bible verse by recalling one of the words in the verse. One can also trace a Bible theme, although care must be taken to understand the words in their biblical context. Also, there will be other words that relate to the theme. A concordance helps you to do a word study, rather than a theological study, of a particular theme.
The same English word may be used by the translation for different Greek words, and several different English words may have been used to translate the one Greek word. Some concordances help clarify this by indicating which Greek or Hebrew word has been translated. A concordance can also be used to find parallel passages, or to trace through the use of a word by one author.