The Lord's Supper or Communion was instituted by our Lord, Jesus Christ on the night when He was betrayed.
On that night, He "took bread, and when He had given thanks, He broke it and gave it to the disciples and said: 'take, eat; this is My body, which is given for you. This do in remembrance of me.' In the same way also he took the cup after supper, and when He had given thanks, He gave it to them, saying: 'Drink of it all of you; this cup is the new testament in My blood, which is shed for you for the forgiveness of sins. This do, as often as you drink it in remembrance of Me.'" (Lutheran Service Book, 326).
These words of Jesus recorded by Matthew, Mark, Luke and St. Paul, tell us what is found in the Lord's Supper: Jesus Christ's true body and blood under bread and wine for us to eat and drink. How shocking and truly amazing that true God would hide Himself under such simple means, yet He does. He does because He desires that we know concretely that we are forgiven of our sins. He does because He desires that our faith is strenthened for the journey ahead, and so it is.