Bhakti yoga is one of the four main yogic paths. It is the easiest of all to practice. Hatha and raja yoga require alot of inner strength and physical health. And jnana yoga requires a subtle intellect. But the only requirement for bhakti yoga is an open, loving heart. Because the practice is so simple, everyone can practice bhakti yoga.
Bhakti means devotion to God. To practice bhakti yoga means to surrender and express genuine love to the almighty One.
In the teachings of bhakti, there are up to 33 million expressions of the Divine One as Gods and Goddesses and Deities. According to advaita vedanta; which is also the support for bhakti; there is only one God or Absolute One. That Divine consciousness manifests itself in many ways. These different aspects of the one God and Goddess, called deities, all represent the Divine On and appeal to different devotees according to their temperaments and personalities.
Bhakti yoga is the devotion and love for God which can be increased through worship. The main practices are called the nine modes of devotion. According to the yogic psychology and the laws of the power of thought, you become what you think. So, to love God/Goddess is to eventually to become one with the Divine.