@ Caroline; by now you should have an appreciation for what a hornets nest this subject is. There are other threads on this subject on FD so search around. You've receive advice from both extremes "never sign NDAs..." and "it's a rookie move..." to "just file a provisional patent...". Like most things, the answer isn't black or white, it's gray.
1. "never ask anyone to sing an NDA - it's a rookie move and you'll be seen as a rookie...just go build...": Be smart about it. Don't ask VCs or angels. They will almost universally tell you they don't sign NDAs. You are way to early to seek funding anyway so there's no reason to be disclosing your secret sauce to a VC or angel investor... so don't ask. Yes, asking a VC or experienced angel investor will most often raise eyebrows. I have only asked on experienced investor to sign an NDA - they did. If you are in fact not a rookie then asking others to sing NDAs won't turn you into one. Never have i been turned down when i've asked someone to sing an NDA. I have had large companies propose their own NDA, but no one has ever said 'no, i won't sign it'.
2. Use your head. Understand what an NDA is for and use it accordingly. An NDA is not the proper method to protect all of your IP - neither is a provisional patent application or a pending patent application for that matter, but i'll get to that in a second. The information you cover under an NDA does not have to be patentable IP, it can be anything you consider confidential. You can't patent your pricing model or list of distribution partners or budget, but you can identify this information as confidential and cover it under an NDA (properly constructed NDA).An NDA is NOT GOING TO PREVENT OTHES FROM DISCLOSING YOUR CONFIDENTIAL INFORMATION. An NDA is an Agreement Not to Disclose information that you identify as confidential. If you don't trust the individual or the individual signing on behalf of the company then DON'T DISCLOSE your confidential information to them, period. Only ask people you trust.
3. " just file a provisional patent": Again, be sure you understand what a provisional patent application is and does and more importantly, doesn't do. A provisional patent application doesn't protect squat other than a date. A provisional patent application is simply a date stamp on an idea you THINK is unique. Patent "priority dates" used to be based on date of invention not filing date. Now the key date is filing date. Don't file a provisional and think your IP is protected. It's not. There is a long road from provisional to issued patent. Your patent application may never issue - turn into a real patent. In the 365 days from the date you file your provisional application you may not be able to afford to file your complete application, then what? You can't file continuations (i don't believe) on provisionals so if you don't file your complete application within 365 days your provisional is abandoned. Then what? Let's say you go around telling everyone you are "patent protected" by your provisional. You disclose you secret sauce. Others think it's interesting. Then you file your complete application. These days patent applications are published - now anyone can have complete access to all the details of your "PATENT PENDING" IP - still no patent. That pending patent may never issue. A patent, which is different from a patent application, won't prevent others from making, using or selling your patented IP and a pending patent application or a provisional sure as hell won't. A patent just gives you a legal basis upon which to sue someone who is making, using or selling your PATENTED IP. Likewise, an NDA won't prevent someone from disclosing your confidential information. When in doubt, don't disclose. If you do disclose and the signer or his/her company discloses or uses your confidential information then what? Are you prepared to sue?
4. SEND A MESSAGE: others may disagree, but i use NDAs primarily to set the stage for partnering discussions and to send a message. I"m not going to carry around a pocket full of NDAs and ask some guy at a meetup to sign before we can start talking. NDAs don't make sense until you've talked long enough to know that BOTH parties are interested in more detailed discussions and WHY they are interested. I only use "mutual" NDAs - NDAs that cover the confidential information of BOTH parties. i do not sign or ask others to sign one-sided NDAs. The message is, "we've talked long enough to know that we are both interested in exploring a possible business relationship. Our future discussions may include information we feel is confidential and you may disclose your confidential information to us. We trust you and you can trust us enough to keep each others confidential information confidential".
5. "I already knew that": Dimitry highlights a good point about people "stealing" ideas. The vast majority of people you talk to don't have the time, knowhow, inclination or resources to run with your idea. Maybe, but highly unlikely. You should have done your homework ahead of time anyway and you now know not to go into your secret sauce in these discussions. That said, NDA's are far from meaningless. A well constructed NDA will have a provision to address the "what if i already knew that" scenario. If Dimitry already had the same idea or knows about someone else who was working on the same idea then fine. It is highly, highly unlikely that Dimitry will be working on your same idea, but if he is then he can prove that he has already been working on it and thus the NDA does not apply to this "previously known" information.
6. NDA's have value beyond the current discussion: If down the road you find yourself in a M&A transaction you will be glad you have signed NDAs and a policy for their use, especially if you also have patents. Let's say you follow a pretty typical startup path: you have an idea, you find a couple of co-founders to help execute (after talking to a bunch who didn't work out), you build a great product (maybe outsourced to a contractor or 2) and then BigCo's attorney calls your attorney and they want to discuss an acquisition. One of the first things on the buyer's due diligence list will be IP and who owns the IP (patented or otherwise). If that programmer you hired to build the MVP didn't sign at least an NDA and preferably an IP assignment provision (in your development agreement) then that's not good - rookie mistake. If every co-founder has a signed NDA on file that's good. If every potential co-founder you disclosed the secret sauce to has signed an NDA, that's good. Showing your buyers that you take your IP and confidential information seriously is good. showing the buyer that "we never ask for NDAs cause it makes us look like rookies" is, well, rookie.
so, in summary, yes, it can be seen as a 'rookie move' to ask others to sign NDAs, but if you don't have enough experience to know whom to ask and when and why and to use the right kind of NDA then your rookiness will be obvious long before you ask for the NDA. Everyone is a rookie at some point. If you have patentable IP then file for patents, but be sure you understand what you are and are not protecting at each stage. Use a well written NDA and use it with the right people for the right reasons.