Operational Security, known as OPSEC, is the process of protecting your planning and actions; safeguarding information on you, your family, or survival group; and preventing potential adversaries from discovering or learning about our preparations. It is used to preserve our plans, safeguard in progress efforts, and protect what has been accomplished. Your overall success will depend upon secrecy so that others cannot target you during a crisis event. The human animal is the most dangerous animal to confront, since he/she is a thinking predator capable of adapting.The idea is that you don't want to be too open about your preps because you will only be inviting trouble in the event of an emergency, be it people showing up at your door, unannounced, seeking food or shelter because they know you are the one that has it together; or looter and thieves seeking out your house because you have the food, guns, stash of gold, or whatever they want to take.
The less information that is known about you and your efforts by others in a crisis, the safer you and yours will be, and the harder for others to target you. A good motto from World War II is “Loose lips sink ships.” This well known slogan is a reference to helping safeguard information on the sailing of troop and supply convoys in the Atlantic and Pacific oceans.
Here is another take on the issue from the Organized Prepper (aka, It's Prepping, Not Hoarding):
As the owner of an ever-increasing food storage supply, I worry about keeping my supplies both private and secure. In addition to The Unprepared thinking that we're whacked-out zombie-obsessed fools, there's the risk of those same people returning to our doorstep if TSHTF.
I tell only select friends and family members about our supplies. In reality, I would certainly help those same people in times of a crisis, so I don't really mind them knowing about my wheat supplies. By the same token, my extreme extroversion causes me to want to spread the word about the joys and comfort that prepping has provided my family. I'm thrilled that my open discussions have led several close friends to begin implementing their own food storage plan.