It is easily understood that, truly, there are as many paths as there are people. Practically though, there are a few hundreds of yogas, or practices which are categorized into the four main paths. These paths are:
Jnana Yoga
The path of wisdom and knowledge. The jnani uses his will and power of discrimination to cut through the veil of ignorance and attain the truth.
For the jnani, the goal is absolute Truth.
Jnana Yoga appeals to the philosophical and intellectual temperament.
Bhakti Yoga
The path of love and devotion. The bhakta uses the combined energies of all emotions and transmutes them, sublimates them into the highest of all emotions: prem.
Prem is pure, conditionless, divine love. For the bhakta, or devotee, the goal is pure love.
Bhakti Yoga appeals to the emotional temperament.
Raja Yoga
The path of self control and self mastery. The raja yogi controls his mind until it becomes perfectly still at which time there is no more wall between himself and his own divine nature.
The main practice in Raja Yoga is meditation. For the raja yogi, the goal is perfect mind control.
Raja Yoga appeals to the mystical and scientific temperament.
Karma Yoga
The path of selfless service. For the karma yogi, the main problem is our inherent selfishness which is based on spiritual ignorance, avidya. The key is to practice selfless actions without any selfish expectations, and thereby opening one's heart and seeing God in all beings.
For the karma yogi, the goal is complete selflessness.
Karma Yoga appeals to the active temperament.