Um, that’s an oxymoron. You are SEEKING to get diluted, and most likely sit a “class below” the capital going into the company. Founders stock is… the stock the founder has/had… I agree with the others that it’s typically the initial common in the company.

Normally I see founders dividing up a brand-new company among them and paying a low price for it. Later (even key) employees generally get smaller percentages and pay higher prices- hence the distinction between “founder’s” shares and other common stock.

The best way I have discovered to protect one’s stock from dilution (from investors, presumably) is to build value in the business. The higher the pre-money valuation the less of the company investors will take. Easier said than done, though.

The other major difference is that Founder’s typically own shares instead of options so they have inherent long term capital gains benefits (since they don’t have to take a hit when exercising the option). It also means that you retain the voting rights associated with the shares instead of waiting until you exercise your options when they vest.

While it’s not part of the stock class, founders can usually negotiate different vesting and other terms as part of their stock restriction agreement upon venture investment. For example, while most employees would see their vesting rest when the Series A round closes, a founder might retain some % of their shares. They might also have special terms in the case of termination or demotion that accelerate vesting. Unfortunately, these have less to do with the type of stock and more to do with who the person is and how strategic they are to the organization.

Hope that helps.