The word LORD is capitalized in place of the word YHWH. The Pharisee Rabbis translated the word for Yahweh to Adonai (Lord) because of the 3rd Commandment's assertion to not take the Lord's name in vain. Over the centuries the Rabbis fiddled with all of YHWH's laws so much that they finally came to the conclusion that God's name was so holy that it shouldn't be uttered at all, even though the Jewish Scriptures tell us we should call on His name.
Finally seeing that doing this would conflict with the actual word "lord" (lower case) that is also in scripture, they had to differentiate between the two words. By capitalizing LORD we now know that it is in place of His name. So when you read lord in the Bible it means just that, lord. When you read LORD in the Bible, it should actually read YHWH (Hebrew for "I am").