A "tithi" is a lunar day in the Hindu calendar, representing the time it takes for the moon to move 12 degrees from the sun. There are 30 tithis in a lunar month, divided into two phases: Shukla Paksha (waxing phase) and Krishna Paksha (waning phase). Each tithi is significant for various religious and cultural practices. Tithis are used to determine auspicious dates for festivals, rituals, and ceremonies in Hinduism. Each tithi has its own characteristics and is associated with specific deities, making them important for planning events like weddings and religious observances.