Stereotypes. Would you like to correct this for me?

Stereotypes, from my point of view, stereotypes can be when someone or something(?) makes a wrong judgment about a person, country ,social groups and so on. We tend to make same mistakes without knowing the truth.
For examples, there are a lot of steretypes related seexual remarks, gender remarks, racial remarks,cultures or groups of individuals among others. So we often hear that men are smaller than women, men are messy and unclean, men spend much time on the computer and read like geeks and things like that. We also hear or we can read in new technologiesy, things like All white Americans are obese, lazy,and dim-witted, or all spaniards enjoy the life, they love dancing, and they are generally considered alive and happy people....
I think , stereotypes must been investigated through observations and after that take out a experimental conclusion. For example in my country really is true that a lot of Spanish people usually speak loudly and in an agressive way, from my view, especially in a bar or restaurant, however there are also Spaniards that speak in a relaxed way, hating loud voices.