n-tier

Question

Heloo experts, I have a doudt please clarify it.

I'll take an example. If the project is in 3-tier i.e.., presentation Tier(PT), business logic (BCT),database. 

If i want to send the data to BCT from the PT then i must send the data  through remoting concept, then BCT code should be in running becoz to create an tcp/http portnumber without portnumber how can we communicate the another server. 

My doubt is if BCT code is running then how it executes the code like is it console project (or) windows project (or) any other

Its a foolish question but i want clear my doubt. please give me an answer.