Question:
What is peace? What is joy?

Answer:
“Peace” we have about anything that happens (good or bad) knowing the Lord is in control of it. “Joy” in John 16:24 is related to the Greek word for grace and thanksgiving.

If I realize more of grace, my heart will respond with thanksgiving and a sense of joy as my heart overflows with gratitude. Joy is the outward expression of thanksgiving.
The Lord has given us His Word that His “joy might remain in you, and that your joy might be full” (John 15:11). The joy that Christ had and has given to us through His Word is despite “happenings.” It is deeper than happiness, which is caused by things that happen. The Lord also gives us peace about that which hasn’t happened. We know that evil may happen, but God is in control (Ephesians 1:11). Peace and joy are part of the fruit of the Spirit (Galatians 5:22, 23).