HIV is a virus which affects how your immune system functions. It is most commonly spread through sex, but can also be spread through sharing needles and through breastfeeding. The spread of HIV can easily be reduced by wearing a condom.
It can take a long time for the symptoms of HIV, which include a flu-like illness, to first start appearing and so many people often live with the virus for years without knowing that they have it, and during this time they can infect many others with it, and this is what makes getting tested so important.
There are two main ways to get tested: