Job agencies are engaged by companies to find them suitable candidates. They may specialise in particular occupations or sectors or cover a specific geographical location. While many of the national recruitment organisations have high street branches, increasingly agencies conduct their operations via the internet using either their own recruitment websites or those most likely to be used by their target candidates.
If you make it as easy as possible for the recruitment company to sell you to an employer, then you will find yourself being put forward for roles. However, if you are unclear about what you want, are difficult to pigeon-hole or seen as difficult to deal with, then you may find yourself being overlooked even by the best recruitment agencies.