If you have recently applied for a job and are waiting to hear back as to whether your application has been successful, you may find the wait quite hard. This may be true especially if you really like the sound of the job that you have applied for or really want to work for the company that is advertising the role. Many jobs will have a closing date for applications then it can often take a week or two (depending on how many applications they have had) before they can start to set up interviews and these may be done in a few rounds.
Often they will tell you when you submit your application as to when you are likely to hear if you have been selected for an interview. Some companies will state that they will only contact you if you have been successful and if you do not hear after a certain date, assume that you haven’t been.
If the deadline has been a few weeks past, then you could give them a call and just check if they are still working their way through the applications although be sure to do this in a very polite manner. If you have applied for a number of jobs and been unsuccessful, you may wish to ask them if they could let you know why. This can be very helpful in progressing with future applications as it can help you see where you have gone wrong.