Getting a patent is a large investment of time, effort and money so it is a good idea to see what is out there before getting too in depth in the project. Sometimes inventors won't yet have an invention that is complete, but would like to get a sense of the patent landscape to determine whether it even makes sense to continue the project and whether there may be some available ‘space' that they could target.
If you think you have a great idea and you're not sure where to begin, a patentability (or novelty) search is the first place to start before exploring patent protection. Having a professional patent search performed on your idea is extremely useful in learning the potential scope of patent rights to be gained and for developing a strategy in preparing a patent application. Remember, getting a patent is a huge investment of time, effort and money so it is an excellent idea to see what is out there before starting the process.