It's impossible to imagine a world without memory.because we can't know anything other than now and we can't learn anything in diffrent courses. memry is a ability for storing and recieving datas. the capacity of the human's memory is limitless. some theories believed that memory have shaped since we can speak but the other ones said that when we were born the memory shaped. however our memory determined by genes. some chemicals like adrenaline can boost up our memory. when we learn something for the first time the memory keep it but the reason of forgetting is that memory fades the datas so we can't access them. we have 3 kinds of memory including sensory,shirt-term and long-term. the sensory memory keep the information until the next comes along. sort-term memory lasts for 30 seconds and the long-term memory is for considering data.finally to sum up we have to reinforce our memory to recall very easily