Techno music originated from Detroit in the mid 80s (around the same time as House was developing in Chicago), heavily influenced by electronic pioneers Kraftwerk and fusing elements of electro, disco and jazz.
Innovators include Juan Atkins (Cybertron), Derrick May, Carl Craig and Kevin Saunderson (Inner City).
Techno is characterised by electronic sounds, 4/4 disco beats (not breakbeats) and heavy bass and is usually instrumental.
It's a different genre to other forms of dance music, such as House, Trance, Big Beat, Dubstep etc
it uses repetitive loops, in similar fashion to the other types of dance music, but is not the same.
It's the original format.
all music that uses repetitive loops is not necessarily Techno, just as all music that uses rapping is not Hip Hop.