There are several reasons:
1. Projects are limited in time. After the project is done, they don't need those developers anymore. They don't have to worry about having a big IS/IT department doing nothing... as it happens so often in Eastern Europe... :)
2. The company doesn't have permanent employees with the requested skills.
3. As Arnon said, an outsider can see things in a different way.
4. An outsider is always ready to do any changes, use new technologies, etc.

Vlad

>Hi Tom!
>
>Thank for answer, but can anybody here explain why big company hire the
>consultant even if this company have fulltime programmers? In my case I
>just have an order from my boss about what to do or not ;)... We never make
>decisions about platform, tools etc.... As result: we work as lazy
>programmers ;)
>
>Have a happy day
>Vladimir Shevchenko
>
>> long as you track yoour time is all that counts.The question is how does
>> an employer know your being honest. The answer is by the work being
>> produced. And to be quite honest how does an employer know if your on
>site
>> that you are actually producing? Really comes down to your track
>> record/reputation.Tom
>>