Miners can decide if they prefer to solo mine or to mine in a pool. Each method has its benefits and drawbacks, but the Monero Project encourages individuals to solo mine using the Monero software (<a href="https://www.getmonero.org/downloads/#gui">GUI</a> and <a href="https://www.getmonero.org/downloads/#cli">CLI</a>), as this type of independent mining is the most effective way to increase the robustness of the Monero network. Mining using P2Pool is also encouraged.
