An important step in meditation training is to learn to develop concentration, i.e. to fix the attention on one point. For most people however, the word ‘yoga’ is associated with the ancient system of physical and mental exercises commonly called hatha yoga. Although a Hindu art, anyone doing Buddhist meditation will find that yoga benefits their practice. Hatha yoga enhances good health, it can be a type of mindfulness of the body and it can invigorate the body after extended periods of meditation.
Yoga is also a Pali term for 'yokes, bonds,' being another name for the 4 fermentations; see asava. In ancient India yoga postures were used for meditation for attaining to formless absorptions such as the jhanas. The Buddha took this a step further, realizing the Dhamma through Insight, Vipassana meditation.
Outside India, the term yoga is typically associated with Hatha Yoga and its asanas (postures) or as a form of exercise. Someone who practices yoga or follows the yoga philosophy is called a Yogi. In many nations now yoga studios have sprouted up for people to come and learn the postures and exercises for better mental and physical health, often with little or no underlying philosophy / religion attached to it.
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952.