Yogic Concepts and Basic Yoga Philosophy (Patanjali, Ashtanga, Hatha)
Patanjali's Yoga Sutras
The text has 196 sutras in four padas: Samadhi (51), Sadhana (55), Vibhuti (56) and Kaivalya (34). Know the key sutras: atha yoga anushasanam (1.1), yogah chittavritti nirodhah (1.2), tada drashtuh svarupe avasthanam (1.3), sthira sukham asanam (2.46), prayatna shaithilya ananta samapattibhyam (2.47) and tatah dvandva anabhighatah (2.48). The five chitta vrittis are pramana, viparyaya, vikalpa, nidra and smriti; the five kleshas are avidya, asmita, raga, dvesha and abhinivesha.
Ashtanga: the eight limbs
Yama, Niyama, Asana, Pranayama, Pratyahara, Dharana, Dhyana, Samadhi. The five yamas are ahimsa, satya, asteya, brahmacharya and aparigraha; the five niyamas are shaucha, santosha, tapas, svadhyaya and ishvarapranidhana. The first four are bahiranga (outer) and the last four antaranga (inner) limbs; pratyahara is the bridge.
Hatha philosophy
Ha (sun) and tha (moon) - balancing heating and cooling energies; hatha also means force or effort. Sources: Hatha Yoga Pradipika, Gheranda Samhita, Shiva Samhita. The Gheranda Samhita describes seven limbs (saptanga): shatkarma, asana, mudra, pratyahara, pranayama, dhyana, samadhi - a favourite exam contrast with Patanjali's eight.
Traps and a rule of thumb
Common traps: placing dharana before pratyahara, counting nine limbs, mixing yama and niyama items (brahmacharya is a yama; tapas is a niyama), and calling asana the third limb of Hatha. Rule of thumb: memorise the order as Y-N-A-P-P-D-D-S and ask whether a listed item is a restraint (don't) or an observance (do). Worked example: if a stem lists shaucha, santosha, asteya, asteya is the odd one out because it belongs to the yamas.