What basic factors must be met for an idea to be considered applicable for a patent?
There are three essential factors that all must be met. If you can meet all three factors, then your idea is eligible for a patent. Of course, they are all subject to a lot of argument, which is why hiring a patent lawyer is a great idea.
This can be summarized with one simple condition: the idea has never been described or claimed in any previous patents. Otherwise, it cannot have been publicly disclosed by someone else in the past (it must not be taken, it must be a unique and novel idea by yourself). It the idea has been described with all of it’s conditions before publicly or in a patent previously filed, then it does not meet this qualification.
Essentially, the idea cannot have been obvious to someone in your specified field. The true test that is applied here (often referred to as the “inventive step”) is if the idea is truly inventive, or if it was too obvious to be considered patent-able.
This is almost always thee easiest requirement to meet. It simply states that you must have a legitimate use for your idea, otherwise you cannot patent it. The idea behind it is to prevent frivolous patents or limiting the scope of patents to only functions it is truly useful in.