Honoring one's parents is one of the precepts found in the Ten Commandments. The Torah tells us, "Honor your father and your mother," and it also says, "Honor God," implying that both precepts are comparable! After all, no matter how much respect we show our parents, we can never repay them for their role in bringing us into the world.
Actually, there are two Mitzvot: to honor and to respect:
To honor means:
Get up from the chair when your parents enter the room.
To serve and assist one's parents whenever possible. To feed, clothe, and provide transportation for them. (If the parents cannot pay for this, the children are obligated to support them.).
Respect means:
Do not sit in their specific place at the table.
Don't contradict them to their face. There's always a discreet way to do this. If not in front of them, you can express a different opinion respectfully.
Saying, "I think you're right, Dad," is also disrespectful; they don't need your approval.
Do not call your parents by their first name.