“Garam” means hot and “masala” means spices. Garam masala is a mixture of spices and varies from region to region and family to family.
I would recommend that you make your own masala mixture as shop bought versions are pallid as cheaper spices like coriander and cumin are used instead of cloves and cardamom.
Spices should be ground or bought in small quantities so they stay fresh and add more flavour.
