Your core business is the primary area or activity that the company was founded on  or focused  on. 

For example, you started your business with the idea of selling women’s wear which comprises of dresses, skirts, scarfs, sweaters, langureau, shoes.  Your core business would be women's wear.   

But after a few months your women’s wear weren’t selling so you decided to start selling things that women may use in their homes such as bed sheets, and window blinds.  That would be a deviation from your core business. 

Instead of going out side of your core business to generate more sales how about adding items that would compliment your core business, such as hand bags, hats, low cost jewelry, etc.  This way you could add more items to your lineup that your customers would be interested in without straying from your core business.  This would both, generate more revenues and enhance customer experience.

Straying from your core business and venturing into areas that don’t compliment each other could be a turn off for your customers.  Imagne if you walked into your local auto repair shop to get your car fixed and they were selling fried chicken as a way to increase their revenues.  You probably won’t find that very appealing.

You should always re-evaluate what you’re doing and seeking feedback from others to ensure that you stay on track with your core business.

Other examples of core businesses include:

 Southwest Airlines:  Provide short trips, cheap fares and good humor.

The Walt Disney Company:  Provide entertainment for all members of the family.

McDonalds:  Serving hot and fresh food in a clean and convenient environment.

Walmart:  Lowering cost in order to offer customers lower prices.