Video narration
Does a Sanskrit word seem to grow a strange vowel when you read it? That surprise comes from two vowels meeting at a word boundary. Instead of keeping both sounds unchanged, Sanskrit joins them and replaces the pair with one predictable sound. That joining is guna sandhi. The strange vowel is predictable: a or a combines with what follows. After a or a, i or i becomes e; u or u becomes o; and r becomes ar. Take deva plus indra. The final a of deva meets the initial i of indra. Apply the first rule: a plus i gives e, so deva-indra becomes devendra. When you meet an unexpected e, o, or ar, look back to the two vowels at the boundary. Remember the pattern: a or a with i or i makes e, with u or u makes o, and with r makes ar. That is guna sandhi.