I recently bought a tiny house since there isn't much space in my city for a big house!
Oh that's cool! It's a whole movement. It advocates living simply in small homes but you know that
I agree, its a movement so save space and protect the environment. 
There currently no set definition as to what size a tiny house is. 
Yea I bet it varies from place to place. What else do you about tiny houses?
Tiny houses on wheels got popular when Jay Shafer designed and lived in his 96sq ft house in 2012
That makes sense, but I certainly couldnt live in a house that small!
The Not So Big House" (1997). Earlier pioneers include Lloyd Kahn, author of "Shelter" (1973) and Lester Walker, author of "Tiny Houses" (1987). Henry David Thoreau and the publication of his book "Walden" is also quoted as early inspiration.
Tiny houses on wheels was popularized by Jay Shafer who designed and lived in a 96 sq ft house and later went on to offer the first plans for tiny houses on wheels, initially founding Tumbleweed Tiny House Company, and
Tiny house movement
The tiny-house movement (also known as the "small-house movement") is an architectural and social movement that advocates living simply in small homes. there is no set definition as to what constitutes a tiny house. However, a residential structure under 400 sq. ft is generally considered a tiny home. The tiny-house movement promotes financial prudence, economically safe, shared community experiences, and a shift in consumerism-driven mindsets.
Background.
In the United States of America