What is voltage?
Voltage or Volt indicates the electical voltage of a lamp. The main power in UK households are usually 230V standard, almost all lamps will work with this standard voltage, howver there are exceptions such as some recessed lights being is 12V.
If you want to convert high voltage (from 230V) to a lower voltage (to 12V) you will need a transformer. A transformer will ensures that the power is converted from 230v to 12v, examples of a transformer is the charger for your mobile phone or the adaptor in your laptop.
It is important to remember the following:
The difference between 12v and 230v, below we list advantage and disadvantages. The advantage of a 12v light is that they last longer because they work on low/less voltage, a disadvantage is that it will only work with transformer. The advantages of a 230v light is no transformer is required and it can be installed straight into your mains also with a 230v can be used with almost all bulbs.