Amitabh posted a collage of images of himself with his co-actors like Shatrughan Sinha and Dharmendra, while several others tried to decode what friendship means.
Here is what the celebrities had to say on Twitter:
Amitabh Bachchan: Happy Friendship day.
Karan Johar: Friendship... the phenomenon that allows you to love someone unconditionally without the pressures and drama of sexual dynamics.
Shahid Kapoor: Happy Friendship Day to all of you and to a friend who is always with me.
Sonam Kapoor: Happy Friendship Day guys!
Anupam Kher: Here is wishing everyone Happy Friendship Day from my side and from my school's side.
Bipasha Basu: Blessed with amazing friends. Happy friendship day to all.
Sunil Grover: As a doctor, I want to wish you a happy very friendship day. What a busy day!
Mugdha Godse: Happy friendship day to all of you... Two good friends and you are the richest person in the world...
Ameesha Patel: A very happy friendship day to all my tweethearts ... You are my family not just friends. So happy family day to all of you.
IANS