1 Intercourse with your spouse: however your can kiss and hug. that will not break the fast.
2 Masturbation: doing this act will also invalidate your fast. according to most of scholars Its also Haram even when you are not fasting.
3 Eating and drinking deliberately: If you eaten or drank something deliberately keeping in mind that you are fasting then your fast will become invalid. however if you eaten or drank something by forgetting then your fast will not be broken.
4 Blood letting: act of letting the blood is also not allowed while fasting. an example is cupping.
5 Vomiting Intentionally: is also Included in the list. however if it happens Unintentionally then your fast will not break.
6 Menstruation, Nifaas: If a women gets menstruation or Nifaas then her fast will end.
so avoid these things when you are fasting. May Allah SWT help us to keep all the fasts this Ramadan.