Hybrids generally have treaded tires which are narrower than mountain bike tires, flat bars, and higher gearing than mountain bikes. They're not quite as fast as road bikes on pavement, and not quite as rugged as mountain bikes on the road. They're good for commuting, and offer a compromise which appeals to a lot of people. These are normally modified mountain or hybrids with more upright riding positions, softer saddles and lower gearing. They re built for, as the name implies, comfort.
Tandems allow two riders on a bike.
Also, a number of companies are offering bicycles with electric-assist motors. The size of the bicycle is critical for comfortable riding. Work with your retailer to determine the proper size for you. The length of your inseam determines the correct frame size, in terms of stand-over height. The reach to the bars is also critical for comfort.