Sex is the first thing that comes to our mind whenever the word Tantra is mentioned. We have been brainwashed by Western definition to think in this manner.
Because the Western interpretation of Hinduism is solely based on their own limited perspective. You cannot define Hinduism the same way you define Abrahamic religions.
What is Tantra?
Tantra is actualy a system of thought or a set of doctrines. It can also be interpreted as governance.
To make it sound simple, any branch of Hindu knowledge is Tantra. There are many types of Tantra. Tantric works are written in Sanskrit. Like the Vedas, Tantras are believed to have been revealed by God to various Sages.
Although the Hindu knowledge systems were originally known as Tantra, the word Tantra itself was replaced with other words. The Shaktas still call it Tantra but the Saivites call it Agama.
The Buddhist have their own school of Tantra in the form of Vajrayana.
The Saivite Tantra/Agama are divided into Siva (10), Rudra (18) and Bhairava (64). Each of the Agamas are further divided into Upa Agama (sub Agama). Many temples built by Tamils follow the Kamika Agama. It is one of the 10 Siva Agamas.
Click to view the list of Upa Agamas http://shaivam.org/agaupaga.htm
Each Agamas can be further categorised as Charya, Kriya, Yoga and Jnana. Constructions of temples is based on the rules laid out in Kriya. We cannot simply build temples as we like. There are rules to follow. One has to be well trained in all these.
This is why in the olden days, the Hindu society had a dedicated sect of people to do it. But nowadays, every Tom Dick and Harry is building temples as he likes. They don't follow the rules.
The holy scripture of the Tamil speaking Saivites is known as Tirumurai. It is written in Tamil. The Tirumurai is divided into 12 books.
Tirumurai #10 is known as Tirumantiram. It was written by Sage Tirumular. He divided the chapters into 9 and each of it is known as Tantra (Tantra 1-9). The verses within each chapter is known as Mantra.
The various Tantras have Dakshinacara (right hand path) and Vamacara (left hand path). The left hand practice has something known as Pancha Makara or the Five Makara.
The Westerners who studied Tantra took bits and pieces from the left hand practices. They then wrongly projected Tantra to the world by only highlighting about some aspects of Maithuna. The world then thinks that Tantra is a perverted sexual ritual.
Tantra is an ocean. It is not right to take a drop from the ocean and claim it to be the whole Tantra. There are many schools of Tantra. Tantric text contains hundreds of thousands of verses.
This entire thing we know about Tantra is just the tip of the iceberg. It will take a lifetime for someone to fully learn Tantra.
Even our Saivite temple priest who are well trained in Kamika Agama may have not fully studied the remaining 9 of Siva, 18 of Rudra and 64 of Bhairava Tantras.
Probably it is simply impossible to learn every single Tantra in Hinduism. Therefore, never let yourself to be fooled again by the misinterpretation of Tantra.
Tantra is not just about sex. It is more than that as Tantra covers many things. Sex is part of life but it is neither the objective nor the definition of Tantra.