The types of agencies
Recruitment firms and databases
These firms operate by searching their own or external databases hosted by job boards for suitable candidates. They also scour social networking sites, such LinkedIn and Facebook, so the reach is extensive. This method of looking for a job allows you to search the job market very easily.
Selection companies approve and select candidates after an ad has been published. This type of organisation gathers, sifts and selects appropriate candidates from applications received.
Headhunters seek candidates who are not actively looking for a job. They specialise in senior and middle management, while conventional recruitment agencies tend focus on lower level positions. Most organisations don't want it to be public knowledge that they're losing a key manager, and so will use a headhunting service to find the ideal candidate who may be working for a competitor. Thus headhunters need to be discreet in the way they work.
If you are approached by a headhunter, proceed with caution:
Make sure that the headhunter really understands the situation well. For example, you might fit the profile they have, but the culture of the organisation may not suit you at all.
Take time to consider carefully whether you want to make the move. When put on the spot, some people can be attracted by a headhunter's proposal. However, in retrospect, the post may not be such a good fit professionally, and may take you away from your desired career path.