Torrent Trackers Explanation Needed

[Elesker]

I have been googling like a mad man but I couldn't find anything.

 

I'm trying to make a list of working trackers for myself but I got confused do to all the differences

 

for example this fake tracker:

 

http://123.45.76.891:9090/announce.php

 

some have UDP instead of http, why is this?

 

so I after the IP comes the port. but is this necessary?

 

some don't even have announce.php or only announce , this gives me the idea its not needed or is it in some-way 'scratches-head' ?

 

Thank you in advance.

[Elesker]

thank you for your fast reply

 

and thanks for the link, no I wont add over 9000 trackers to the list