IP protection before approaching VC
Before approaching VCs, is it recommended to start patent process or some way to ensure protection of IP? Does it happen that some VC rejected an idea but gave away someone else refined or similar idea?
You'll need to spend a little bit of time learning how to write a patent description. It's a tedious (rather than say, hard) thing to do, but is a great skill to learn anyway.
Once you get the hang of it, getting a provisional patent for any or your ideas is quite easy. Then you shouldn't have any qualms about divulging any aspect of your idea to anyone.
You can legally say that your idea or product is 'patent pending' with a provisional patent. This may sound silly to some, but will definitely sway a serious investor. Like them or not, patents are powerful.
As I said, this buys you a year. That should be enough time to determine if the idea is worth the time and expense to obtain a full patent.
The day you launch everyone will know what you're doing. If you're too slow too launch someone will beat you to it. Patents will not protect you from competition. Rely on your insight into the problem and ability to execute.
A more general answer might be useful: VCs are just one of the groups you might talk to, and most of the time you're not onto something big, and the most valuable thing for your time is to share the idea and hear the truth. Telling people your idea also lets YOU refine it. Working a bubble usually ends up meaning you work longer on the idea before you finally unveil it, and start to refine it.
The refining, the iteration and the hustle are what matter.
Good luck!
If you are focused and domain knowledge on what you are working on, to solve a real world problem. They will be dying to invest in you.
If you are not the right person to solve that problem, and your idea/product is amazing. You should be make an IP and find for experts who can help you with that.
It also depends on what you are building. If you are BT you should definitely patent it.
But if it's not complex you don't need any kind of IP.
VCs are in it to make money just like anyone else and if your idea (like a detailed one with implementation and specifics) is good, you can expect them to poach/take the idea similar to what Huli did in the TV series Silicon Valley.
PS. If your idea is consumer-tech, it may have less value than say a patent on some powerful way to extract 100% energy from solar power (or more industrial stuff).