Do Not Expect To Be Hired On The Spot.
Candidates must realise that interviewers usually are not there to hire anybody immediately. They are only trying to make a screening decision to determine whether the company should talk with you further. By the end of the interview, most companies will try to spell out as clearly as possible what to expect next. (Whom any further action will come from and when.)
How Companies Tell You They Are Interested
Even when interviewers think a candidate is highly qualified, they will rarely promise anything because they canot be certain what their company might decide later. They may encourage you to try to build interest in working for the company, but they will not make promises. A candidate under active consideration can usually expect an invitation to a second interview, usually at a company location, or a request for more information within a short time.
How You Can Tell Them You Are Interested
If you have a strong interest in a company, you may write to the interviewer confirming that interest. You should mention the interviewer's name, time and date of the original interview, plus any important points discussed. Another good way to demonstrate interest in a company is to demonstrate knowledge of it. Candidates, especially those already invited to a second interview, should research the company on the web, read the annual report, company literature, and anything they can find about the company if they have not already.
How They Tell You "No!"
During an interview, it sometimes becomes obvious that a candidate's interests and a companys opportunities simply do not match. A good interviewer will frankly, but courteously tell the candidate, saving each party time.
In many cases, candidates who are not offered a job will be informed within a few weeks of the interview. In other cases, candidates may not receive any further correspondence unless a suitable position is identified before their date of availability.
A negative reply may dent your ego, but almost everybody hears a "No" or two before they land a job.
Source: Sunday Times