A provirus is formed when the viral gene is incorporated into the host cell's genome.
Retroviruses are examples of proviruses because they can infect the host cell, integrate their genome, and produce more viral particles by controlling the cell division mechanism.
Formation of provirus:
The proviruses are thought to be the first form of life on Earth.
According to H.M Temin's research, they are the ancestors of viruses that were present on Earth, and modern viruses evolved from them.
He also stated that they were able to perform reverse transcription, which is the process by which DNA is formed from RNA.