Thanks a lot for the information.
I have been offering services on a particular name say "ABC" for the past 5 months without having a trademark. If someone else applies for a trademark on "ABC" and sues me for using his/her TM is there a possibility for my firm to defend itself as we were the first to use the name(based on domain name registration, etc).
My doubt regarding website is not yet clarified. If I get a TM for "ABC" is it obvious that I am the only one who can have a domain by name www.ABC.com? Or putting it in a different way, if I get a TM on "ABC", if some XYZ starts a website by name www.ABC.com, can I sue him?
If some other firm is dealing in similar products/services and launches its products/services with a very identical name though not exactly the same, can I take action against it?