At its simplest a Campervan is a van or similar that you could, as a minimum requirement, sleep in. People have used their ordinary panel vans, put a mattress in the back and set off! Modern Campervans are just up market versions of this traditional basic.
Many people have the skills to convert their minibus or van or indeed any other large enough vehicle into a Campervan as a DIY project or they can use a professional company to convert it. As a minimum the van will need windows fitting and perhaps a roof extension. There are a range of other things to consider from sound and heat insulation to space heaters, cookers and fitted cushions for the beds. The conversion can be cheap or as high-end and plush as your pocket will allow.
A critical part of the conversion are the windows – they can be bought single paned or double glazed. Double glazing is a major benefit for sound and heat insulation and these windows can looks very smart. Usually supplied in an assembly ready to install – some stylish with grey acrylic double glazed pane and black frames together with integral roller blind and fly net.
With the windows fitted then thoughts can begin of installing running water or installing second batteries and sorting the electrics.