Strong's Concordance (strictly Strong's Exhaustive Concordance of the Bible) is a concordance of the King James Bible (KJV) that was constructed under the direction of Dr. James Strong (1822–1894) and first published in 1890. Dr. Strong was Professor of exegetical theology at Drew Theological Seminary at the time. It is an exhaustive cross-reference of every word in the KJV back to the word in the original text. It included:

• The 8674 Hebrew root words used in the Old Testament. (Example: Hebrew word #582 in Strong's)
• The 5523 Greek root words used in the New Testament. (Example: Greek word #3056 in Strong's)

James Strong did not construct Strong's Concordance by himself; it was constructed with the effort of more than a hundred colleagues. It has become the most widely used concordance for the King James Bible.

Each original-language word is given an entry number in the dictionary of those original language words listed in the back of the concordance. These have become known as the "Strong's numbers". The main concordance lists each word that appears in the KJV Bible in alphabetical order with each verse in which it appears listed in order of its appearance in the Bible, with a snippet of the surrounding text (including the word in italics). Appearing to the right of scripture reference is the Strong's number. This allows the user of the concordance to look up the meaning of the original language word in the associated dictionary in the back, thereby showing how the original language word was translated into the English word in the KJV Bible.

New editions of Strong's Exhaustive Concordance of the Bible are still in print (in 2006). Additionally, other authors have used Strong's numbers in concordances of other bible translations, such as the New International Version and American Standard Version. These are often also referred to as Strong's Concordances.

Although the Greek words in Strong's Concordance are numbered 1–5624, the numbers 3203–3302 are unassigned. Not every distinct word is assigned a number, but only the root words. For example, αγαπησεις is assigned the same number as αγαπατε—both are listed as Greek word #25 in Strong's "αγαπαω".