As long as white blood cells are sufficient and the number of HIV viruses is low, there is almost no sign. In these conditions, white blood cells carry out their duties of defending the body against diseases, while HIV also survives and proliferates in white blood cells and the person has no signs. These conditions may continue for many years.
As the number of viruses increases, white blood cells resources and power are consumed to meet the needs of the HIV, and their ability to perform their functions (defending the body against other diseases) gradually diminishes and disappears. If this process continues, the immune system will gradually lose all its ability to resist other germs and diseases, and if exposed to any other germs, the person will become infected and show signs of that disease. This stage is called AIDS, when symptoms of other infectious/non-infectious diseases (opportunistic infectious) appear.