@samira rai ,
back in the old days, employers would let you know if you got the job by phone.
if you didn't get it, they sent you a standardized letter in the mail.
nowadays, if you don't hear back from them, assume you didn't get the job.
but you should still contact them for confirmation.
some companies take months before they decide on a new hire,
especially if they interview a lot of people for it...