Very possibly a dumb question

i'm just smart enough to use utorrent, and in a very general i understand how it works, but i have one
question.

when i'm dl'ing a torrent using utorrent and in the seeds column it says "5(9)" and in the peer column it
says 6(13), why am i not connected to all of them instead of only 5 and 6 respectively?

i click on the "peers" tab and it shows who i'm connected to, and sometimes it shows a long list of people,
but i'm only dl'ing and ul'ing to some of them. don't understand that either. can someone explain?

thanks. your answer is helpful. i'll look up handshaking. and if anyone has anything to add please do.

i agree with the spirit of numaris' answer, but i always thought that rtfm was a
bit mean.

one of your answers is, afaik;
you are uploading the parts that you have, to people that don't have them?
you are downloading the parts that you haven't, from people that do have them?

then again,there r excellent wiki pages about this, not even all wrong.
as soon as wiki is not political, it's not a bad source
but don't consult it for racism, capital punishment, or borders of rhode island,
coz those wikis change every hour ... 😉