Earlier adultery was an offence under section 497 of the IPC.
It provided that any man who knows that woman is married and then enters into a sexual relationship with her was to be punished.
This section treated woman as the property of the husband and hence after the long legal battle the apex court of India in Joseph Shine V. Union of India case decriminalised the offence of adultery. From now on adultery is not punishable however shall remain a ground for divorce.
Shayra Bano is a famous case where 'triple talaq' was made illegal.
While Navtej Singh case is one LGBTQ (home sexuality) was also decriminalised.