Dinank(Tithi) plays a special role in Hindu Sastra.
Panchang is a Hindu calendar and in the Daily Panchang, where the details of a particular day are given, in the Monthly Panchang, the details of the entire month are given. Monthly Panchang i.e. a month in the Hindu calendar is divided into 30 days. These 30 days is divided into two sides. In which one Paksha of 15 days is called Shukla Paksha and the remaining 15 days is called Krishna Paksha. The more and lesser phases of the Moon are called Shukla and Krishna Paksha.
Let us know the importance of these two aspects in Vedic scriptures.
Krishna Paksha
The part between the full moon and the new moon is called Krishna Paksha. The day next to the full moon day marks the beginning of the Krishna Paksha, which lasts for 15 days until the new moon day. Auspicious work is not done in Krishna Paksha. It is believed that whenever there is Krishna Paksha, it is not appropriate to do any auspicious work during that time. Actually, behind this, there is a decreasing phase of the moon in astrology. As the day progresses after the full moon, the moon decreases. That is, the light of the moon starts getting weaker. With the decrease in the size and light of the moon, the nights start getting dark. For this reason, also Krishna Paksha is not considered as auspicious. Tithi of Krishna Paksha - 15 days (Purnima, Pratipada, Pratipada, Tritiya, Chaturthi, Panchami, Shashti, Saptami, Ashtami, Navami, Dashami, Ekadashi, Dwadashi, Trayodashi, Chaturdashi
Shukla Paksha
The part between the new moon and the full moon is called Shukla Paksha. The 15 days after Amavasya are called Shukla Paksha. From the very next day of the new moon, the moon starts rising and the dark night starts shining in the light of the moon. On full moon day, the moon is very big and full of light. During this time, the Moon remains strong in its full size, that is why this aspect is considered suitable and best for doing any auspicious work. Tithi of Shukla Paksha - 15 days (Amavasya, Pratipada, Pratipada, Tritiya, Chaturthi, Panchami, Shashti, Saptami, Ashtami, Navami, Dashami, Ekadashi, Dwadashi, Trayodashi, Chaturdashi)
If you also have faith in Panchang, then do your special work in Shukla Paksha only.