Detergents, chemically known as alfa olefin sulphonates (AOS) are used as fabric brightening agent, anti-deposition agent, stain remover and as a bleacher. SO, detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions. They are family of compounds that are similar to soap but are more soluble in hard water, because the polar sulfonate (of detergents) is less likely than the polar carboxyl (of soap) to bind to calcium and other ions found in hard water. A major input for the production of detergents is a petrochemical, Linear Alkyl Benzene (LAB), while soaps rely more on an inorganic chemical, caustic soda, as a major input.

Chemically detergents are classified as Anionic detergents, Cationic detergents, Non-ionic and zwitterionic detergents.

Typical anionic detergents are alkylbenzenesulfonates. The alkylbenzene portion of these anions is lipophilic and the sulfonate is hydrophilic. Two different varieties have been popularized, those with branched alkyl groups and those with linear alkyl groups. The former were largely phased out in economically advanced societies because they are poorly biodegradable. An estimated 6 billion kilograms of anionic detergents are produced annually for domestic markets. Effectiveness is even greater when combined with non ionic detergents.  Soaps and many synthetic detergents are anionic. Its advantages are can safely be use in waxed or unwaxed floor, very effective in removing organic dirts and soil but they are not very effective in hard water and produces considerable foam. Cationic detergents are similar to the anionic ones, with a hydrophobic component, but, instead of the anionic sulfonate group, the cationic surfactants have quaternary ammonium as the polar end. The ammonium center is positively charged.  Dish and hand washing soap falls under this category such detergents have low foam characteristics, have anti- static property and are effective in repelling dust, very effective as a bactericide, disinfectant and deodorizer. But the disadvantage with such detergent is that they are more expensive than anionic and non ionic detergents,  used alone than these detergents are ineffective and are usually combined with  non- ionic detergents for better cleaning effectiveness. Nonionic detergents are used in dish washing liquids. Since the detergent does not have any ionic groups, it does not react with hard water ions. In addition, nonionic detergents foam less than ionic detergents. The detergent molecules must have some polar parts to provide the necessary water solubility. They can be used with a wide variety of cleaning equipment with low foam properties in the better alkaline detergents. Such detergents are use on all surfaces, produces less foam then anionic detergents and are effectively used in conjunction with scrubbing machine or other cleaning equipments, easy to rinse. But the disadvantages of such detergents is  they are less effective than anionic detergents in the wetting of metal surface, more expensive and are mostly available in liquid form. Zwitterionic detergents have characteristics of both ionic and non-ionic detergent types. Zwitterionic detergents are less denaturing than ionic detergents and have a net neutral charge, similar to non-ionic detergents. They are more efficient than non-ionic detergents at disrupting protein-protein bonds and reducing aggregation. These properties have been used for chromatography, mass spectrometry, and electrophoresis methods, and solubilization of organelles and inclusion bodies.Limited qualities are used in shampoos, medicated liquid soaps and aerosol shampoo.

Detergents are available as powder, bars and liquids. Its major applications are in laundry, in most household contexts, where the detergents refers specifically to laundry detergent or dish detergent, fuel additives where  both carburetors and fuel injector components of Otto engines benefit from detergents in the fuels to prevent fouling, biological reagents where reagent grade detergents are employed for the isolation and purification of integral membrane proteins found in biological cells. With so many vital application of Detergents, it has become an important source of income for various industries such as the bar market which is dominated by Hindustan Lever (now Hindustan Unilever - HUL) having its brands - Rin, Wheel, 555, Shakti, OK. Hindustan UniLever was the first to launch the powder detergent, Surf, as far back as 1959. A decade later it came up with detergent bars under the brand name Rin. . The market was further extended by the HUL in mid-1980s by introducing low cost detergent bars and powders under the brand name Wheel. Wheel is the low cost detergent bars and powders and it is HUL's leading detergent brand and contributes around 50% to the revenues of the company's laundry business. Earlier, several small scale informal sector operators appeared on the scene which also included Nirma. Nirma emerged as a major player threatening the market leader, HUL. Nirma became the leader in the powder detergent market by its unique new low-priced product in direct confrontation with Hindustan Lever.

Bars make up for less than half of the market, while powders have more than a third of the market. Liquids have 12% presence in the market. As mentioned above the bar market is dominated by Hindustan Unilever while the super-premium market, making up for around 10% of the overall detergents market, is dominated by Surf Excel from HUL and Ariel from Proctor & Gamble (P&G). The two together have a near 75% market with the rest coming in from players like Henkel SPIC. Henkel Spic is a 47% subsidiary of German detergent leader, Henkel AG. It has a wide product portfolio consisting of detergent powders, bars, dishwash bars, liquids and cleansers, with a good presence in the southern market. In the sub premium segment, Nirma from Nirma Soaps and Wheel from HUL are the major brands with small presence from an array of brands like Trilo, Hipolin, Tide, Key, Chek and others. Ghari is one of the fastest growing brands especially in North India. It has a market share of around 40% in UP and Bihar with close to 10% share on an all-India basis. The detergent market in India is dominated by HUL, Nirma is the second largest player with an overall market share of 19%. Nirma is more dominant in the states of Gujarat, Rajasthan, Punjab and Haryana, that is Northwest India. Nirma has the highest market share of around 40% in Gujarat. It has the highest market share in the mass segment, like toilet soaps.

NIIR Project Consultancy Services (NPCS) has published below mentioned books on soaps & detergents, which can be useful to know more about subject.

• Modern Technology of Soaps, Detergents & Toiletries (with Formulae & Project Profiles) 3rd Edition
• Handbook on Soaps, Detergents & Acid Slurry (3rd Revised Edition)
• Herbal Soaps & Detergents Handbook
• The Complete Technology Book on Detergents
• Selected Formulary Book on Cosmetics, Drugs, Cleaners, Soaps, Detergents, Dentrices and Depilatories
• The Complete Technology Book on Soaps
• Soaps, Detergents and Disinfectants Technology Handbook