What are filenames that are preceded by a dot?

Ronan is a Caffeine dependent life-form from Planet Earth who wants to be a Jedi Knight of cloud computing. A man of mystery and power, whose power is exceeded only by his mystery. Quantum Physicist, TransHumanist, Systems Architect, Unix Administrator, Artificial Intelligence, Machine Learning and DIY Gadget enthusiast. Believes that the Universe has a high probability of being a simulation.
But he's real and hopefully some of his readers are too.
email: Ron.Jagannathan@gmail.com ph: 202 355 5205
https://www.linkedin.com/in/ronjagan/
My Famous Quotes:
“In a Unix Universe, God is known by a four letter word called root. To err is human...to really foul requires you to be root.. err.. god.” ― Ron Jagannathan

Github: github.com/ronjag
Linkedin: linkedin.com/in/ronjagan/

“Quotes found on the Internet are not always accurate.” ― Abraham Lincoln