An idea is a defined as a “formulated thought or opinion”. An invention is a “unique or novel device, method, composition or process. It may also be an improvement upon a machine or product, or alternate means of achieving a process”.
Ideas aren’t patentable —only inventions are.
If you are a “serial inventor”, ideas probably come to you all the time. Often inconvenient times like when you are trying to sleep or in the middle of a conversation when someone thinks you are listening to them. Ideas can be as simple as a thought that may lead to a sketch depicting the vision in your mind or a list describing the attributes of the idea.
Good idea should evolve in shape, size, color, definition, substance, functionality, attributes etc. making it more viable for the market where it can be used. The idea may change completely due to the new changes and discoveries, reaching a totally different target audience than originally envisioned. The idea can also die… which should be a common and a healthy part of an inventor’s life. Just ask Edison.
An invention on the other hand is usually the end result of an idea that has matured. It is more “tangible” or defined and can be legally patented, licensed and/or trademarked.
Investors like to hear both – ideas and inventions. Of course, the further an idea has matured the better chance of getting a licensing contract to bring your idea to market if that is your intention.
The important thing is to jot your idea down… anywhere… so that you do not forget that “ah ha!” moment only to remember it when you see that head slapping infomercial that stole your idea. Consider getting an “Inventor’s notebook” to write down idea or at least get used to texting a note to yourself on your smartphone or computer soon as you have the idea. If it’s the middle of the night, writing down the idea will usually allow you to get back to sleep.
The current patent laws protect people who can prove they are first to invent. These laws change however in 2013, siding with the person who is first to file. The type of Inventor’s notebook you have (page numbered, bound, dated, signed by you and a witness etc.) could prove that you had the idea first if you try to fight it in court but that can be an expensive uphill battle.
Research the competition to your idea thoroughly and if your solution is still meaningfully unique, take the next steps toward launching your invention. If your idea is good enough to make money, then it may be wise to formally patent or service/trademark your idea, turning it into an invention before someone else profits from your great thinking.