How much to give 'Zakaat'

Salaam alaikum,

could you all please tell me who is enjoined to give zakaat? and how much?

I only know if he possesses a lot of money but how much and whom to give zakaat? to beggers u see on the street or someone who is seeking zakaat?

pls respond with all the answers of zakaat, and also what is fitra? while u reply im gonna google it as well