What is "Dot product operation" ?

This sure may sound as stupid question. I assume that this is some kind of mathematical operation. But I am not an English native and I have had many classes of math even on university but not in English. I have notices from the texts where it appears that this has to do something with the math. If so I am sure I shall know how to use it I just do not know the equivalent in my native language.
If it is not concerning something mathematical but sth graphical it is probably going to be harder. But if You can suply me with some sources where to begin with studying this subject it would be great.
“Dot product bump mapping” “Dot product”. I think this has nothing to do with “dtos”,i.e. points.
So if You know, please help me.

in general terms the dot product is usually found in linear algebra texts…

the dot product of two vectors v1={x,y,z} and v2={a,b,c} would be:
xa + yb + z*c

Thanx. I knew it is sth that bloody simple. I just could not figure what specificely except that it shuld have to do sth with vectors but they were not always mentioned in appropriate text.
Too bad I could not find it in my English dictionary. I think that for graphics OpenGL programming there shall one more book needed and that is Mathematics but in English language. I have already realized many such English words and symbols, just from the context of the problem, that are not in the dictionary (dictionary is a dictionary and not a math book after all, or not ?) but there sometimes arises such a word.

That is exactly what is in Red Book when calculating normals. Just two sentences or so.

Thanx anyway.