Rudra

Shiva shares many features with Vedic Rudra. In Hindu scriptures (Purana) both are viewed as the same personality. Hence, Shiva is the Puranic form of Vedic Rudra. The earliest mention of Rudra is found in Rigveda, Yajurveda  and Atharvaveda.

The evolution of Hindu Religion centers around two important periods, namely Vedic Period and Puranic period. During Vedic period, God was represented by nature and emotions. For example Indra was God of Thunder, Agni was God of Fire, etc.

Rudra represents God of Fear and things that create fear, such as high winds, storms, hurricane, typhoon, lightening, etc.

In Sanskrit, RU means frightening and DRA is superlative meaning – mightiest or greatest. Hence Rudra can be concluded as mightiest or greatest roarer or creator of fear. During the Puranic period, Brahma, Vishnu, Shiva and Shakti (divine feminine power) came into existence as the greatest powers. At the same time, the Vedic Gods were transformed into Puranic Gods.

Both Rigveda and Yajurveda recommend the worship of Rudra (Shiva) to get Moksha, by reciting what is popularly known as Maha Mritunjaya mantra. In the various recital recensions (shloka, mantra, etc.) of Yajurveda, a number of stanzas praising Rudra are found. Together they are known as Shata Rudriyam. On Mondays, Lord Shiva is worshiped by reciting what is known as Rudra Namakam and Rudra Chamakam.

* Source: https://en.wikipedia.org/wiki/Rudra

Nandikeshwar

Nandi idol at Shri Sai Temple at Dapoli, Maharashtra.
Courtesy: Shri Sainath Maharaj Trust Dapoli

Sri Nandikeshwara or Nandi is a very important deity, since he is the only witness to the creation of the Universe and all beings therein through Shiva-Shakthi. So praying to him will bestow us with spiritual knowledge, and enhance our receptiveness of the Lord's grace. Nandi is also the embodiment of intuition and instinct. That is why it is said that we should look at Lord Shiva from in between Nandi's horns. That way, we can perceive and receive the Lord's grace by maximizing our instinctive and intuitive abilities. 

An idol of Nandi is commonly seen at all Shiva temples facing Lord Shiva, signifying constant and silent conversation with the Lord. He is regarded as the Lord's mount, is the foremost of the Ganas (followers of Shiva), and is a gatekeeper at the Lord's door. He is most often depicted as a Divine Bull, and sometimes as having a human body with a Bull's face. There are temples in India solely dedicated to Nandi. Devotees are often seen whispering their wishes in Nandi's ears, since it is believed that all sincere & pure wishes conveyed to him will be granted. According to shaiva siddhanta Nandi is the chief Guru of 18 siddha munis. The word Nandi is derived from sanskrit word which means happy or joyous person.

Mythological Legend 

To obtain the nectar of immortality Devas and Asuras performed the churning of the ocean using Mount Mandara for a churning rod, perched on Maha Vishnu in the form of the Kurma (Tortoise) Avatar for stability; and the serpent Vasuki for a churning rope. The asuras pulled the head-end of Vasuki, and the Devas took the tail-end. Several cosmic forces and divine objects emerged from the ocean. 

During the process, Vasuki - the King of the serpents emitted out the deadly poison Hala-Hala, which represents the remaining karmic residuals of all living beings in the past creation and dissolution cycle, and which would have wiped out all earthly creations, and threatened the very existence of all divinities. Lord Shiva came to the rescue, along with Nandi. Lord Shiva collected the poison in the palm of his hand, drank it, and held it in his throat. Hence, he is also known as Neelakantha (one with a blue throat). At that time, Nandi observed some poison spilling out of Lord Shiva's mouth, and immediately drank it to prevent it from harming others. The Devas and Asuras were at once concerned if Nandi could survive the poison. Lord Shiva assured them that Nandi was so steeped in devotion towards him, that he had access to all of Lord Shiva's powers and his complete protection. 

According to another legend Sage Shilada meditated on Lord Indra and did a severe tapasya to have a child with immortality. Indra advised him to pray to Lord Shiva to get the boon. After a long period of tapasya the body of the sage was eaten away by termites. Lord Shiva gave darshan to the sage and restored him to his old form. He gave him the boon to have a child with immortality. Shilada performed a yagnya for getting a child. From the yagnya a child appeared clad in the armor made of diamonds. After some years the deities Mitra and Varuna informed the sage that the boy would have a short life. Worried by the message of the deities Sage Shilada did tapas to please Lord Shiva. Lord Shiva blessed the child and declared that he would be worshipped along with him and will be his mount. There are other instances in the purana where Nandi is mentioned. In almost all the Shiva temples Nandi is located in front of Shiva Linga. Some puranas mention Nandi as the chief of Shiva’s army. Spiritually, Nandi represents an individual jiva (soul) and the message that the jiva should always be focused on Atman (Paramatma).

Some of the famous temples of Nandi are 1) Brahadiswara temple in Tamil Nadu. Chamundi hills in Mysore. Rameshwaram temple and Nandi temple at Khajuraho.

Ardhanarishwara

Source: wikipedia

Ardhanarishwara is one of the manifestations of Lord Shiva. Literally it means the lord who is half male and half female. The legend behind this form of Lord Shiva has its reference in several puranas and the epic Mahabharata. In almost all the major puranas there is the mention of Ardhanarishwara. The kshetra-purana in Tamil narrates the event that led to this manifestation. Once, all the sages and munis gathered at Kailash to pay their respects to Lord Shiva and Parvati. Sage Bhringi, who had vowed to worship only Lord Shiva, ignored Parvati. Enraged by this sage's behavior Parvati cursed Bhringi Rishi to become only a skeleton losing all his flesh and blood. On seeing this condition of sage Lord Shiva blessed him with a third leg so that he could stand erect. Parvati who felt defeated performed severe tapasya to please Lord Shiva. Lord Shiva granted her the boon of uniting with him so that Bhringi Rishi will be compelled to worship her along with Lord Shiva in the form of Ardhanarishwara. But the sage assumed the form of bumblebee and circumambulated only the male half of idol by drilling the hole in idol of the deity. Amazed by the devotion of the sage Parvati reconciled with the sage and blessed him. 

In the Kalika purana, Gauri is set to have suspected Lord Shiva of infidelity when she saw her own reflection in the breast of Lord Shiva. A conjugal dispute erupted and was resolved quickly. Parvati expressed a wish to fuse with Lord Shiva. Accepting her request Lord Shiva fused with Parvati to form Ardhanarishwar. In Shiva Purana the legend states that Brahma created Prajapatis who were all males so they were unable to create. Brahma approached Lord Shiva for help. Lord Shiva appeared as Ardhanarishwara at the request of Lord Brahma and a number of female beings were created to Ardhanarishwara for the creation to progress.

The idol of Shiva in Ardhanarishwara form is found in almost all Shiva temples in South India and South East Asia. The main temple is at Thiruchengode in Namakkal disctrict in Tamil Nadu and also in Rishivandiam near Kallakurichi in Tamil Nadu.

Navaratri

Navaratri festival is dedicated to Goddess “Durga”. During this festival, Devi is worshiped in 9 different forms. This festival generally lasts for 9 nights and 10 days. Sometimes it may last for 9 to 11 days. Last day i.e. 10th day (generally, but this time as per tithi it is 11th day) is celebrated as Dasera. This festival is celebrated all over India, Nepal and wherever Hindus reside in the world. There are 5 different Navaratris mentioned in Puranas. Of these, Sharad Navaratri is the most popular one and also known as Maha-Navaratri. 

1. Shakambari Navaratri (Paush Navaratri) – This is celebrated in the month of Paush. It begins on Paush-sukla Ashtami and ends on Paush Pournima. Paush Shukla Ashtami is also known as “Banada Ashtami”. Shakambari Devi is an incarnation of Devi Bhagawati. She took this incarnation to feed the sages and all living beings during the great famine. Presently this is celebrated in Karnataka, Andhra, Maharashtra, Uttar Pradesh, Rajasthan and West Bengal.
2. Vasant Navaratri – This is spread over 9 days during which Shakti is worshiped. It is observed in the month of Chaitra Shukla Paksha. The beginning of Vasant Navaratri also marks the beginning of Lunar calendar Vikrami Samvatsar. This Navaratri is also known as Chaitra Navaratri as it occurs in month of Chaitra.
3. Aashadha Navaratri – It is also known as Gupt Navaratri. It is a 9 day festival dedicated to Goddess Varaahi. Generally this is performed by sadhakas. It involves tantrik rituals for Satkarma (good deeds).
4. Sharad Navaratri – This is commonly known as Maha Navaratri and celebrated all over the world by Hindus. It is considered to be most important. It begins on Shukla Pratipada in month of Ashwin and may last 9/10/11 days according to Tithi.
5. Maagh Navaratri – It’s a Gupt (गुप्त) Navratri celebrated mostly in Punjab, Haryana, Himachal Pradesh, Uttar Pradesh and Uttarakhand. It is celebrated during the Shukla Paksha in the month of Maagh. It is generally observed for getting protection from evil forces, danger, injury and destruction etc. It is observed by the sadhakas for obtaining Riddhi & Siddhi.

In South India during Sharad Navaratri the first 3 days Devi is worshiped as Durga, next 3 days as Laxmi & last 3 days as Saraswati and 10th day is known as Vijayadashami.

Below is table that lists different offerings on each day of Navaratri

Day	Devi	Navratri Color	Devi’s Pooja name	Flower	Specialty of day	Naivedya
Day 1	Durga	Grey	Maheshwari/ Koumari	Jasmine (Mogra)/ Bilva	Madhu-Kaitabh Samhar	Fruits
Day 2	Durga	Orange	Trimurtini	Jasmine (Chameli)/ Tulsi		Mango & Tamarind rice
Day 3	Durga	White	Varahi/ Kalyani	Champak/ Sweet majoram (Murwa)	Mahishasur Vadh	Sweet Pongal
Day 4	Laxmi	Red	Mahalaxmi / Rohini	Pink Jasmine (Gulabi Chameli)	Mahalaxmi Avatar	Curd Rice
Day 5	Laxmi	Royal Blue	Vaishnavi/ Kalika	Fragrant flowers	Shumbh-Nishumbh meet Devi	Pongal (Rice with Toor daal, black pepper & salt)
Day 6	Laxmi	Yellow	Indrani/ Chandika	Parijat, Saffron flower	Chandika Avatar	Orange & Coconut rice; Pomegranate
Day 7	Sarswati	Green	Mahasaraswati/ Shambhavi	Jaswanti, Ketaki, Tamba flower	Maheshwari Avatar	Lemon rice
Day 8	Sarswati	Peacock Green	Narasimhi	Champa, Henna flower	Sarswati Avatar	Kheer made of rice, milk & sugar
Day 9	Sarswati	Purple	Subhadra/ Chamundi	Lotus, Dawana	Tripursundari Avatar	Sweet Pongal
Day 10	Mahishasur Mardini	-	Ambika	-	-	-

Mostly in North India during the Navaratri 2016, the pooja will be performed as given below.

Day 1 – Shailputri Pooja

Day 2 – Chandra Darshan

Day 3 – Bramhacharini Pooja

Day 4 – Chandraghanta Pooja

Day 5 – Kushmanda Pooja

Day 6 – Skandamata Pooja

Day 7 – Katyayani Pooja (Saraswati avaahan)

Day 8 – Kalaratri Pooja

Day 9 – Saraswati Pooja, Durga Ashtami, Mahagauri Pooja

Day 10 – Mahanavami Pooja

Day 11 – Vijayadashami Pooja