How To Count From First Loop To Last

I made this "lesson" to get the result of a pyramide which I succeded but not understand why im affraid..The thing is I dont understand exactly how to count it.. Isnt "j" incrementing every loop ?? In my head it should be just one star per line( the height is set to 3)how to count from the first loop to the last?I understand that println change the line though, but not why j would loop more than one time on each line..

for(int i = 1; i <= height; i++){
for(int j = 0; j < i; j++){
System.out.print("*");
}
System.out.println();
}
}
}

result:

*
**
***