Classical yoga under Patanjali has 8 different "limbs" of yoga. The first "limb" is the Yamas or social contracts. The second "limb" are the Niyamas or contracts with oneself. The third "limb" is Asana or yoga poses, there are hundreds! The fourth "limb" is Pranayama or breath. The fifth "limb" is Pratyahara or turning inward! The sixth "limb" is Dharana or concentration.
In my opinion Dharana , is sense concentration, is focusing!
Concentrate! How many of you remember these exact words from your childhood?
Focus on your work, your task at hand. Concentrate. Focus.
Bringing the mind into a single focus.