What is it

Theano is a package for performing tensor calculations, useful in training neural networks.

(In Greek mythology, Theano was a priestess of Athena in the city of Troy. See wikipedia.)

This is software I have mainly utilized as a backend to Keras, not interfaced with directly.

End of Life

Development on Theano by MILA will officially end around the end of 2017:

2017/09/28: IMPORTANT: MILA will stop developing Theano and the next release (renamed to 1.0) will be the last main release.

It is still a useful package, but it won't be actively developed by MILA.