Jesus said in Matthew 5:17, “Do not think that I came to destroy the Law or the Prophets. I did not come to destroy but to fulfill.” The Greek word translated, "fulfill," means to bring to completion, give true meaning, perfect or accomplish the goal. Jesus came to bring the Law into its mature form that it always was intended to become. This “maturing”, involves change in form, but not in its ultimate goal, which was always the revelation of the character of God for us to follow so that we can be like God.
One way to think of this is like the growth of a child. When a child is young, there are laws and commands that are appropriate for him that would not be appropriate for him as an adult. Laws for young children, say two years old for example, need to be very black and white and the punishments clear. A parent living on a busy street may make a law stating that the child may never run into the street for any reason. A two year old is not mature enough to evaluate when or when not to enter a busy street. Therefore, the law is clear, and if they disobey Dad and Mom, punishment is swift for the benefit of the child. However, a twenty year old may realize that it's not smart to enter a busy street but he may need to depending on the situation. It would be totally inappropriate for a twenty year old’s parents to still have a law concerning entering the street with the same punishments. The principle remains, but the law changes to fit the maturity.
Another way to look at it is the building of a magnificent throne for a king. While the throne is being constructed there are rules to follow to ensure its solid build. Clamps may need to be in certain places, or it may need to be upside down until the glue sets. There are tools you would use in the beginning that you would never use once it’s in its completed state. When the time is right, the clamps come off, never to be used again. Its finished state is much more glorious than the beginning state, but without the clamps, the throne would never have been built right.
The laws of the Old Covenant are like those laws for a young child and like the clamps/tools needed at the beginning of a construction. Jesus came to bring the child to maturity; to take off the clamps and set the throne in its place to serve the King. Now let’s take a look at some of the important laws that Jesus changed and brought to fulfillment.