Patent applications must satisfy the following three criteria: Novelty. This means that your invention must not have been made public – not even by yourself – before the date of the application. Inventive step. This means that your product or process must be an inventive solution. Industrial applicability.
Yes, you can sell an idea without a patent, but it's more challenging. Without patent protection, it's harder to prevent others from using your idea without compensation. To protect yourself, consider using non-disclosure agreements (NDAs) when discussing your idea with potential buyers.