Cooling products are probably the most hard working appliance that you will own, they are one of the few that have operate 24 hours a day and in wide range of temperatures. Being that they have to operate 24hours a day it's worth looking closely at the energy efficiency of the cooling products as moving to a higher efficiency model can save you money on your electric bills.
Frost Free / NoFrost / Static / Lowfrost / Smart Frost
When choosing a fridge freezer you will see them referred to as any one of the above.
Frost Free / NoFrost, these freezers have a fan the circulates the air within the freezer compartment and capture any moisture present, for a short time each day they will automatically defrost. This saves you the hassle of manually defrosting. Most frost free freezer will occasionally need defrosting, this can occur when the too moisture is present in the compartment, normally because the door has not been closed correctly or food has been places in the compartment that is not in a sealed bag or container. It is also important not to over fill a frost free freezer as this will prevent the air from circulating and again lead to ice build up. Frost free freezer can cost a little more to run and have less room due to the vents and fans.
Static, these are freezers that need defrosting manually, how often depends upon the environment that the freezer is in. In a warm moist environment then they will need doing more often. The more often you open and close the door on a static freezer will also lead to more ice build up. To defrost a static freezer its best to switch off the freezer remove the all food to another freezer and let the ice melt naturally. It can be helped on its way by placing a bowl of warm water in to the freezer. Don't be tempted to attack the ice with a knife or boiling water as this can damage the insulation and sensors within the compartment. One often overlooked effect of excess ice build up is that it dramatically effects the energy efficiency of the appliance and they cost significantly more to run.
Low Frost / Smart Frost, these are a clever compromise between frost free and static, they have moved the cooling elements in to the walls of the compartment and often have a glass shelf between each drawer. The shelf helps prevent moist air circulating around the compartment. The gaps around the drawers are often smaller to prevent moist air rushing in when you open the door. All of these measures help significantly reduce the amount of ice build up, making them easier to defrost and without compromising the energy efficiency or space in the freezer compartment.