what is matter?

everything that suround us is made up od matter.the air,the animal,rocks,plants,everythiong.we could define matter as all that occupies space and can be weighed.even gassses which are very an inflated balloon we can see that it weighs slightly more than un.inflated balloon.when we are studing matter we lengt,surface,area,vilume,mass,density or termperature.so that we are old using the same unites in science,we used what is called the international system of unites.