What is the definition of Chalav Yisrael?
Milk or dairy products are referred to as Chalav Yisrael (Israel Milk) if they were produced under constant rabbinical supervision from milking through packaging.
So it is defined in the about.com article “What is Chalav Yisrael?”
The web page about Chalav Yisrael on the web site for Chabad states:
The kosher laws stipulate that all dairy products should be Chalav Yisrael (lit., “Jewish milk”): a Torah-observant Jew must be present from the milking to the end of the processing to ensure that only milk from kosher animals is used.
You can read that entire aricle by clicking here, and then you might wish to go over to read The Making of Chalav Yisroel that starts out with:
For many centuries, there was absolutely no question that the milk in a Jewish home was chalav Yisrael.
Read the rest of that over here.
Continue your education about Chalav Yisrael by reading the following (just click on the title for a new browser window to open with the entire article):
Chalav Yisrael: Is it Required?
Does Chalav Yisrael Apply Today?