Hindus regard it as an earthly manifestation of the goddess Tulsi, a consort of the god Vishnu. The offering of its leaves is mandatory in ritualistic worship of Vishnu and his forms like Krishna and Vithoba.
Read more in this thread...
It is considered holy as it has been blessed by Lord Vishnu himself and burns away sins of a person.
Tulasi plant on earth is actually a form of Laxmi. As per Devi Bhagavatam, due to a quarrel among Saraswati, Ganga, Laxmi, Saraswati cursed Laxmi to be born as a plant on earth
Laxmi being favorite of Vishnu, He then consoled Her by stating that everything had happened as predestined. So He told Her to go and be born and as a plant in India.
She will be known as Tulasi and will be able to purify all the three worlds
Also, as per Garuda Puran planting, preserving, watering, touching and worshipping Tulasi tree burns away a persons accumulated sins of many births:
The esoteric importance: Tulasi as lila-shakti (the pastime energy of the Supreme Lord) is a division of sandhini-shakti (the all-encompasing unifying energy). Sandhini-shakti itself is one of the three principal energies of the Lord Sat from sat-chit-ananda.
Tulasi as Vrinda-devi grants one entrance into the ashta-kaliya-lila or the intimate pastimes of Krishna. Neither Brahma, nor Shiva can do that.
The Padma Purana declares a person who is cremated with Tulsi twigs in his funeral pyre gains moksha and a place in Vishnu's abode Vaikuntha.
If a Tulsi stick is used to burn a lamp for Vishnu, it is like offering the gods lakhs of lamps.
If one makes a paste of dried Tulsi wood(from a plant that died naturally) and smears it over his body and worships Vishnu, it is worth several ordinary pujas and lakhs of Godan.
Water mixed with the Tulsi leaves is given to the dying to raise their departing souls to heaven.
One of the best Tulasi experts in the world, Bhakti Visrambha Madhava Swami has collected great original materials on Tulasi , this video tells more about it.
Tulasi is a devotee of Lord Vishnu (Kesava priya) and she is said to practice vratam/fasting on Ekadasi and so as not to disturb her in potentially weak condition people don't pick her leaves on the following day.
In some traditions days besides Ekadasi are also followed for various religious practices and the same rule seems to apply.
there are many things described in a book called Nitya Karma Puja Prakash, which is in hindi. The book in its Deva Puja section is describing the rules ,mantras and procedure to pluck plant leaves like Tulsi ,Bilva and other flowers .
"The wretch that abuses Mûla Prakriti, the Vedas, the S’âstras, Purânas, Brahmâ, Visnu, S’iva and the other Devas, Gaurî, Laksmî, Sarasvatî and the other Devîs, goes to the hell named Bhayânaka Narakakunda. (continue)
- Devi Bhagavata Purana 9.33.
There is no other hell more tormenting than this. The sinners live here for many Kalpas and ultimately become serpents. There is no sin greater than the abuse of the Devî. There is no expiation for it. So one ought never to abuse the Devî. (continue)
However, discard the desire (kama) and material wealth (artha) if contrary to Dharma; as also, any usage or custom or rules regarded as source of Dharma if at any time they were to lead to unhappiness or arouse people's indignation.
Manu Smriti 4.176
THIS DOES NOT, in any way, mean that one is free to make up his own notions of dharma, nor does it mean that one should change dharma if they don't like it.
What it actually means is what the commentator Medhātithi says:
"Or, again (one should avoid), such acts as are ‘disapproved by the people,’ as being blameworthy...."
How do we find out our Ishta-Deva (personal deity)?
Ishta Devata is the personal Deity who will guide the soul to its real home--Moksha.
There are 3 possible ways, in our opinion, that Ishta Devata is chosen by a spiritual aspirant. #thread
Here are first 2 ways. 1. A spiritual aspirant becomes attracted to a particular Deity after reading through different spiritual literature and accepts that Deity his Ishta Devata; and
2. The Guru of the spiritual aspirant meditates and finds out about the person's Ishta Devata.
The 3rd way is based on astrology and here is brief introduction about it based on A blog of Dr. Anjna Agarwal.
It will go little technical from here, so hold on some patience
The key role in revealing one's Ishta Devata plays the Atma Karaka.
What are the solutions to reduce the difficulty of Kali?
Srimad Bhagavatam has answers to all the doubts regarding Kaliyuga.
Lets see that answers in this thread.
The sages were worried about the Kali Yuga to ask Suta Goswami this same question.
Ugrashravas Sauti (Suta Goswami) was the narrator of several Puranas, with the narrations typically taking place before the sages gathered in Naimisha Forest.
In response to this, the text Srimad Bhagavatam was spoken by Suta Goswami to all present.
The following 7 verse from Srimad Bhagavatm are essence of reasoning given to King Parīkṣit by Śukadeva Gosvāmī to explain him why Hari Kirtan and Bhakti Marga is the best way to reduce effect of Kali.
The First chapter is called by a self-contradicting title. It is named as the Yoga of ARJUNA'S GRIEF. If 'grief' could be Yoga, almost all of us, without a choice, are already Yogins.
These are very important commentary from Swami Chinmayananda in his book "Holy Gita"
He indicated that the Arjuna-condition of utter despair is the auspicious mental attitude wherein the Geeta-seeds are to be sown, and the flowers of Krishna-perfection gathered.