Because labor laws outside the US can make it difficult to fire someone, many companies will add more barriers before you are a full-time employee at the company with benefits. They will make employees work during a probation period before deciding to offer full-time employment. Contract-to-hire is another common way that this manifests ("try before you buy").
Here are some tips if you're working on this model:
Relevant discussion: I’m starting at Apple with a 3 month probation as a new grad. How should I think about the probation period?