Lakshmi is the Hindu goddess of wealth, light, wisdom, the lotus flower and fortune, and secondarily of luck, beauty, courage and fertility. Representations of Lakshmi (or Shri) are found in Jain and Buddhist monuments, in addition to Hindu temples. She is also kind to children and gives presents. Due to Her Motherly feelings and being the consort of Narayan (Supreme Being), She is believed as the Mother of the Universe.
She is the consort of Vishnu and married his incarnations Rama (in her incarnation as Sita), Krishna (as Rukmini) and Venkateshwara (as Alamelu). In Vaishnava traditions, She is believed to be the Mother Goddess and the Shakti of Narayan.
The appearance of goddess Lakshmi is related to an ancient story. Durvasa the short-tempered sage once presented Indra, the king of the gods (devas) with a garland of flowers which would never wilt. Indra gave this garland to his elephant Airavata. Sage Durvasa saw the elephant trampling the divine garland and cursed Indra, for he had shown disrespect to the sage. The sage cursed Indra that he and all the gods would lose their power because it had made them so proud and vain. Due to the curse, the demons vanquished the gods out of the heavens.
The defeated gods then went to seek refuge to the Creator Lord Brahma who asked them to churn the ocean of milk, Ksheersagar, to obtain the nectar of immortality. The gods then went to Lord Vishnu, to seek his assistance. Lord Vishnu took the Avatar Kurma (Tortoise) and supported the Manthara Parvata (mountain) as a churning rod, while the king of the serpents, Vasuki, became the churning rope. The gods and the demons (under the leadership of the pious and wise King Bali Chakravarti) both helped each other in churning the ocean of milk.
Amongst the host of divine gifts which appeared from the ocean, goddess Lakshmi appeared and then chose Shri Vishnu as her consort, as only He had the power to control Maya (illusion). Because of this, Lakshmi is also called the daughter of the sea; since the moon also appeared from the ocean during the churning, the moon is called her brother. Alakshmi, the goddess of misfortune, is Lakshmi's older sister. She is said to have also arisen from the sea of milk. 
According to the Vishnu Purana, Lakshmi is the daughter of Bhrigu and Khyaati and resided in Swarga but due to the curse of Durvasa, she left Swarga and made Ksheersagara her home. The reappearance of Lakshmi after Samudra manthan and her marriage to Vishnu thereafter, remain the same. Laxmi is the power and Maya of Lord Vishnu. In some places She is seen in two forms, Bhudevi and Sridevi, both either side of Vishnu. Bhudevi is the fertility form in which She is Mother Earth. Sridevi is the wealth and knowledge of Her which is seen with Narayan. Most people are mistaken that they are separate beings although they are one, Laxmi.
Goddess Lakshmi means Good Luck to Hindus. The word 'Lakshmi' is derived from the Sanskrit word Laksya, meaning 'aim' or 'goal', and she is the goddess of wealth and prosperity, both material and spiritual.
Lakshmi is the household goddess of most Hindu families, and a favorite of women. Although she is worshipped daily, the festive month of October is Lakshmi's special month. Lakshmi Puja is celebrated on the full moon night of Kojagari Purnima.
The Lakshmi Form
Lakshmi is depicted as a beautiful woman of golden complexion, with four hands, sitting or standing on a full-bloomed lotus and holding a lotus bud, which stands for beauty, purity and fertility. Her four hands represent the four ends of human life: dharma or righteousness, kama or desires, artha or wealth, and moksha or liberation from the cycle of birth and death.
Cascades of gold coins are seen flowing from her hands, suggesting that those who worship her gain wealth. She always wears gold embroidered red clothes. Red symbolizes activity and the golden lining indicates prosperity. Lakshmi is the active energy of Vishnu, and also appears as Lakshmi-Narayan - Lakshmi accompanying Vishnu.
Two elephants are often shown standing next to the goddess and spraying water. This denotes that ceaseless effort, in accordance with one's dharma and governed by wisdom and purity, leads to both material and spiritual prosperity.
A Mother Goddess
Worship of a mother goddess has been a part of Indian tradition since its earliest times. Lakshmi is one of the mother goddesses and is addressed as mata (mother) instead of just devi (goddess).
As a female counterpart of Lord Vishnu, Mata Lakshmi is also called 'Shri', the female energy of the Supreme Being. She is the goddess of prosperity, wealth, purity, generosity, and the embodiment of beauty, grace and charm.
A Domestic Deity
The importance attached to the presence of Lakshmi in every household makes her an essentially domestic deity. Householders worship Lakshmi for the well being and prosperity of the family. Businessmen and women also regard her equally and offer her daily prayers.
On the full moon night following Dusshera or Durga Puja, Hindus worship Lakshmi ceremonially at home, pray for her blessings, and invite neighbors to attend the puja. It is believed that on this full moon night the goddess herself visits the homes and replenishes the inhabitants with wealth. A special worship is also offered to Lakshmi on the auspicious Diwali night.