Competition is most often seen as coming from other persons, companies or organisations, but it is equally common that you create your own competition for a product that you have.
For example, if you make a hamburger, and you then also offer a pizza, the pizza is competition for the hamburger and visa versa. While the sale of either a hamburger or a pizza represents income for you or your company, if you only sold the same number of hamburgers as you sold of hamburgers and pizzas, and assuming the profit margin was more or less the same, by specialising in hamburgers you probably would save costs as you will not have to buy ovens to make the pizzas or stock a variety of toppings to put on the pizzas, or have to spend time and money making/buying the base. In saving these costs associated with offering different products and selling less of each, your profit margins would grow, and you would make relatively more money selling a fixed number of a single product (i.e. hamburgers) versus selling the same number, but made up of different products (i.e. hamburgers and pizzas). However, businesses will often produce a variety of products