Please, thank you, sorry — the words that keep you polite.

• لطفاًlotfanplease
• ممنونmamnunthank you (common, informal)
• متشکرمmoteshakker-amthank you (more formal)
• خواهش می‌کنمkhâhesh mikonamyou're welcome / please (polite)
• ببخشیدbebakhshidsorry / excuse me
• معذرت می‌خواهمma'zerat mikhâhamI apologize (formal)
• بلهbaleyes (polite)
• آرهâreyeah (informal)
• نهnano
• البتهalbatteof course / certainly