Hinduism/Religious Symbols of Hinduism
The Om Symbol 
Aum or Om (in Devanagari ॐ) is one of the most sacred symbols in Hinduism. In Sanskrit known as praṇava (प्रणव) lit. "to sound out loudly" or oṃkāra (ओंकार) lit. "oṃ syllable")
Hindus consider Aum to be the universal name of the Lord and that it encompasses all of creation. It is made up of the letters A (as in "around"), U (as in "put") and M (as in "mum"). The sound emerging from the vocal cords starts from the base of the throat as "A." With the coming together of the lips, "U" is formed and when the lips are closed, all sounds end in "M." The "amen" in Christianity and the "ameen" in Islam and "aum" may show a common linguistic ancestry within the Indo-European language group and it is conjectured that the Aum mantra may have travelled from the East to Europe changing its form and context. Judaism contains the first recorded use of "amen" in the context of a response by the congregation to the priest's prayer. Judaism defines the Semitic verb "amen" as meaning "to be trusted".
Om symbolizes The Supreme Personality of Godhead i.e Parabrahman. It symbolizes the prana or life breath with runs through one's body bestowed by the Parabrahman. The significance and explanation of Om is given in the Mandukya Upanishad.
Hindus believe that the entire essence of the Vedas (ancient Indian scriptures) is enshrined in the word Aum. The belief that the Lord started creating the world after chanting "aum" and "atha" gives this religious symbol a fundamental relevance to the Hindu view of creation. Hence, its sound is considered to create an auspicious beginning for any task that one may undertake.
vedyam pavitram omkara What is to be known, that I'm the purifier and the syllable OM.
Some devotees see similarities between the shape of Ganesha's body in iconography and the shape of Aum in the Devanāgarī. The upper curve is the head and the lower large one, the stomach; the side one, the trunk; and the semi-circular mark with the dot, the sweetmeat ball (modaka) in Lord Ganesha's hand. For Hindus, Aum is seen as a fundamental component of the physical and metaphysical tenets of Hinduism - the means and the goal of life, the world and the Truth behind it, the material and the Sacred, all form and the Formless.
Aum is one of the most chanted sound symbols in India. It is believed to have a profound effect on the body and mind of the one who chants it. It is placed at the beginning of most Hindu texts as a sacred exclamation to be uttered at the beginning and the end of a reading of the Vedas or as the beginning to any prayer or mantra..
It may also be used as a greeting - Aum or Hari Aum . Its form is worshiped, contemplated upon or used as an auspicious sign within the Hindu religion. Today, in all Hindu art and all over India and Nepal, 'Aum' can be seen virtually everywhere, a common sign for Hinduism and its philosophy and theology.
The Swastika Symbol 
The swastika (from Sanskrit svástika) is an equilateral cross with its arms bent at right angles, in either right-facing form or its mirrored left-facing form. Archaeological evidence of swastika-shaped ornaments have been dated to the Neolithic period and was first found in the Indus Valley Civilization of the Indian Subcontinent. It occurs today mainly in the modern day culture of northern India, sometimes as a geometrical motif and sometimes as a religious symbol.
In Hinduism, the two symbols represent the two forms of the creator god Brahma: facing right it represents the evolution of the universe (Devanagari: प्रवृत्ति, Pravritti), facing left it represents the involution of the universe (Devanagari: निवृत्ति, Nivritti). It is also seen as pointing in all four directions (north, east, south and west) and thus signifies a grounded stability. Its use as a Sun symbol can first be seen in its representation of the god Surya (Devanagari: सूर्य, Sun). The swastika is considered extremely holy and auspicious by all Hindus, and is regularly used to decorate items related to Hindu culture. It is used in all Hindu yantras (Devanagari: यंत्र) and religious designs. Throughout the subcontinent of India, it can be seen on the sides of temples, religious scriptures, gift items, and letterheads. The Hindu deity Ganesh (Devanagari: गणेश) is often shown sitting on a lotus flower on a bed of swastikas.
The Bindi Symbol 
A bindi (from Sanskrit bindu, meaning "a drop, small particle, dot") is a forehead decoration worn in South Asia (particularly India) and Southeast Asia. Traditionally it is a dot of red colour of sandalwood paste, turmeric or vermilion applied in the center of the forehead close to the eyebrows, but it can also consist of a sign or piece of jewelry worn at this location. The tilak (Sanskrit: Tilaka means “mark”) is also used by men to show religious affiliation or by both sexes after a puja ritual to invoke religious feelings
Nowadays, bindis are worn throughout South Asia (India, Bangladesh, Nepal, Sri Lanka and Pakistan) by women and girls, and no longer signifies age, marital status, religious background or ethnic affiliation. The bindi has become a decorative item and is no longer restricted in colour or shape. Self-adhesive bindis (also known as sticker bindis) are available, usually made of felt or thin metal and adhesive on the other side. These are simple to apply, disposable substitutes for older tilak bindis. Sticker bindis come in many colors, designs, materials, and sizes. Fancier sticker bindis are decorated with sequins, glass beads, or rhinestones.
Outside South Asia, bindis are sometimes worn by women of Indian origin. Some Western women who have converted to Hinduism, such as in the Hare Krishna movement, also wear bindis. Sometimes they are worn as a style statement. International celebrities such as Gwen Stefani, Shakira, Madonna, Nina Hagen, Nelly Furtado, and Shania Twain have been seen wearing bindis.
A bindi can be called:
- Tikli in Marathi
- Pottu in Tamil and Malayalam language
- Tilak in Hindi
- Chandlo in Gujarati
- Bottu or Tilakam in Telugu
- Bottu or Tilaka in Kannada
- Teep (meaning "a pressing") in Bengali
The area between the eyebrows (where the bindi is placed) is said to be the sixth chakra, ajna, the seat of "concealed wisdom". According to followers of Hinduism, this chakra is the exit point for kundalini energy. The bindi is said to retain energy and strengthen concentration. It is also said to protect against demons or bad luck.
In addition to the bindi, a vermilion mark in the parting of the hair just above the forehead is worn by married women as a symbol of their married status. During North Indian marriage ceremonies, the groom applies sindoor on the parting in the bride's hair.
The Sacred Thread 
The Yajnopavita (sacred thread) is given to male Hindus to signify their spiritual awakening and acceptance as religious students. The ritual is usually reserved for males from the Brahman (priest) caste, the Kshatriya (military or ruler) caste and the Vaisya (merchant-traders) caste. The scared thread is actually three intertwined threads symbolic of the Trimurti. The threads also represents three of the Vedas texts- the Rigveda, Samaveda and Yagurveda. The Artharaveda is not included. The knot in the middle of the sacred thread represents the eternal and divine force of all creation (Brahman). The thread is never meant to be taken off and a devout Hindu will bathe or swim with it on. It is hung diagonally from the left shoulder to the waist. It is placed over the right shoulder during funerals. The material of the thread may be cotton or wool not hemp. The person undergoing the ritual is referred to as "twice born". The biological birth is his first birth and after the sacred thread is placed, the symbolical acceptance of a spiritual teacher as father and the Vedas as mother signifies a second birth. The initiate will shave his head and wear new clothes and during the ceremony a priest or guru will recite the Gayatri mantra. At the close of the ceremony a traditional dakshina (gift) is given to his teacher.