How do people have twins?

I want to know the process how it takes place???

search over the net

Well, there's not really any trick like having sex a certain way to get twins, but sometimes, spontaneously, instead of sperm going into the egg and it turning into one cell, sometimes it turns into two separate ones, causing twins

Identical twins, sometimes called "paternal," occur when a female egg splits and forms two embryos. Non-identical, "fraternal" twins develop from two separate eggs, each fertilized by separate sperm cells.

There are many ways. Sometimes and egg can split, and this can cause fraternal twins. Sometimes women make more than one egg during ovulation and sperm attaches to both, causing her to be pregnant with non-fraternal twins. Your chances are increased if twins run in your family. Also some say diets help, like lots of diary and yams. Women that are older and/or overweight tend to produce more eggs, and are more likely to have twins.
Also, some people become pregnant with twins on purpose with IVF. That is very expensive though.