If you have recently applied for a job and are waiting to hear back as to whether your application has been successful you may start to get a little concerned if it seems to be taking a while. 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.
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 or if you haven’t been successful. Some job postings will say if you haven’t heard back after a certain time to assume you were unsuccessful. 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 may be something like you have not got certain experience or a qualification they require. This will then allow you to check if you can do something about then before applying for similar positions.