Method of Heating
There are many different methods heaters use to heat. One of these is the ceramic heater, which is able to heat quickly and is less dangerous than an open flame. It is also very cost effective and energy efficient. Similarly, reflective heaters are also quite energy efficient. They replicate the sun's healthy rays (no UV) to heat an area, and are also non-flammable. Radiant heating works much the same way except that this method heats surfaces rather than air, and the surfaces then radiate heat outwards to warm the air. Another method of heating is micathermic heating, which combines the technologies of convection and reflective heating. Micathermic heaters heat up almost instantly and distribute heat more evenly than traditional heaters. They are also very energy efficient, but can be costly. Finally, there are radiators, which use oil to heat up metal coils and radiate heat into the room.

Portability
Some heaters come with casters so they can easily be wheeled from room to room. Others are very light and are easily carried to another room, while others are too heavy or large to move or they are mounted or installed which prevents them from being moved.

Functions
Some heaters can do more than just heat. For instance, some heaters also function as air purifiers, and some can be used as only a fan so they can still be used in the warmer months. Others even include a humifier to keep your environment from drying out. Additionally, some heaters are oscillating so the heat can circulate through the room more easily, and some have more than one fan speed so you can control how powerful the hot air is blown into the room.

Safety Features
It's important to know what safety features come with a heater, particularly if you have children or pets or will be keeping it near water or flammable materials. Safety features include overheat protection to keep the unit from becoming dangerously hot, water-proofing to prevent electrocution, and auto shut-off so that it does not become a fire hazard if left unattended. Many freestanding heaters also come with tip-over protection so if they fall down they will not destroy your flooring. Most of them also feature a non-flammable surface. These are just some of the safety measures manufacturers have designed to protect your home and loved ones.

Controls
Heaters come with either manual or digital controls. Manual controls are easier to use, but digital controls allow you to set the exact temperature you want your room, rather than a relative temperature. Digital units also often come with a remote control and a timer.