प्रत्यय (Suffixes) are added after a root or word to form new words. Two main categories: कृत् प्रत्यय (added to धातु/verb roots — forms कृदन्त words like कर्ता, कर्तव्य, कृत) and तद्धित प्रत्यय (added to noun/pronoun stems — forms derived nouns/adjectives like मानवता, राजकीय, बालकी).

Important कृत् प्रत्यय: क्त (past participle — गत, कृत, पठित), क्तवतु (past active — गतवान्, कृतवान्), तव्य/अनीय (obligation — कर्तव्य, पठनीय), तृच् (agent — कर्ता, धाता), ल्युट् (action — गमन, पठन), शतृ (present participle — गच्छन्, पठन्), शानच् (present middle — सेवमान). Important तद्धित प्रत्यय: मतुप् (possession — बलवान्, धनवान्), त्व (abstract — मनुष्यत्व), ता (abstract — मानवता), इक (relating to — वैदिक, ऐतिहासिक), ईय (relating to — भारतीय, राजकीय).

REET Exam Tips: Most common question: identify प्रत्यय in given word, or match root+प्रत्यय=word. Know the difference between कृत् and तद्धित. Key trap: 'गम' is a धातु not a प्रत्यय — तुरंगम does NOT use 'गम' as प्रत्यय.