Welcome.
As we hear the "Virus", we immediately think of "oh shit!!". Most peoples think that computer virus totally destroy computer. But that might not be true. As I am the computer science person, I am surrounded with so many people having laptops and desktops. Most of them are computer students. They keep sharing of their programs, assignments, reading materials like ppt & pdf files to one another with medias like pendrive and memory cards.
When you insert your pendrive or memory card into computer, and if your computer has virus, that virus will try its best to enter into pendrive or memory card. Its intention will be to be spread using such medias. So when you insert this pendrive or card in another computer, the most probably this computer will be affected by this virus.
Today there are so many free and paid antiviruses are available. But they need to be updated continuously. Because viruses are created almost everyday. So people get infected in PC or laptop easily by surfing internet or by using infected storage medias.
The problem with me was started in 2009 when I was student of computer science. We had a dedicated lab for internet. When I used my pendrive there, most of time it was infected by viruses. So I started the study of virus' behaviours and how they can be identified. When I could identify them, I thought and experimented to remove them manually, I mean without using any antivirus. Ultimately I started removing most of viruses which I found in my pendrive, my computer, friends' computers and students' computers. When students and my friends got their computer infected by virus, they comes to me.
I have seen that, people come to me for removing viruses even they have a good antivirus. They suffered from virus even they have antivirus, because antivirus is a program and any program has limits.
Upto now, I have removed approx 200+ computer's viruses. Of course, without using antivirus. Ya, I use some tools like cmd, regedit, task manager etc.
Now, Its my passion. When I find any computer with virus infection, I just take it and start hunting for viruses. I like to hunt computer viruses. When I get virus in my pendrive, I just say "hurrrraayyy!"
Thanks.