Fish sauce has been with Thai cooking a long time. Thai people in the past normally produced their own Thai fish sauce, by fermenting some kind of fresh water fish with salt in a jar. They would bring these fermented jars of fish out in the sun until there was liquefied in the jar. Then they would carefully sieve the liquid out. The more they brought the jars out to dry in the sun, the better the quality of the fish sauce. Some families would put some kinds of herbs such as lemon grass or lime leaves into the jar to enhance the favour and smell of the fish sauce. The result being each families fish sauce would have a different taste and smell.
Long time ago, Thai people have used fish sauce to enhance Thai food, Thai food nowadays would not have a perfect flavour without it. Most Thai food will not taste better with just salt or soy sauce.
Still Thai people do not use only fish sauce, they sometimes use salt and fermented salty fish to enhance some kind of foods which are normally local or native foods, especially food from rural areas or made by poor people.
There is a tip about using fish sauce that if we want to use fish sauce in Thai curry, we should put fish sauce after the other ingredients (sugar, other sauces) and should do it when curry is boiling. We should pour fish sauce into a spoon first because if you pour fish sauce directly into the pot or pan, fish sauce might leak and add to much.
Nowadays most Thai people do not produce their own fish sauce, due to there are many factories that produce it. Which is more convenience than produce their own.
