The extruder is the most important part of the 3D printer. It is the piece which heats up the plastic fillament to a melting point and then deposits the melted drops through a nozzle to form the desired model on the platform. It is attached to a fan to prevent the extruder from overheating and for temperature control. This is a single extruder, which means you can only use one color at a time.

This double extruder is the same as the single extruder except that it comes in 2 heads. Which allows for adding a second color to the 3D printer. Please note that the printer still will not use 2 colors simulataneously. It will use one color at a time, but at least a second color will be readily available. Not very practical if you only use one color for your models.

The nozzle is attached to the extruder. It squeezed the fillament to the desired diameter (ie. 0.4mm). The finer the nozzle the better the quality of the 3D models. However if the nozzles are very small, it will take a longer time to print and also there is a higher risk that the nozzle will get cloged (jamming).

The motor is what makes the extruder move into 3 axes (XYZ): X (left to right) Y (back to front) Z (up and down). So most 3D printers should have 3 motors. Knowing the 3 mentioned axes will help you also position the 3D object before you print it out.

The fillament is the plastic rolls which the 3D models are made of. Think of it as the ink for the printer. The fillament comes in ABS or PLA.
ABS vs. PLA: ABS is made of polymer and can take many forms and can be engineered to have many properties. It is a strong and more flexible plastic (compared to PLA). However, the smell is stronger than that of PLA. PLA is plant based (corn, potatoes or sugar-beets), and thus is considered 'earth friendly' and less smelly compared to ABS.

The platform is where the 3D model is created. The extruder deposits tiny drops of fillaments on the preheated platform, layer by layer until the model is finished. When the platform is cooled down, removing the model from the platform becomes easy.

Suitable for use for Thermal insulation of 3D printer beds. It allows the plastic to stick to the platform when hot, but releases easily after cooling.