What are modernist ideas?

Historically it referes to the period at the turn of the last century, when the industrial revolution promised an exciting change in industry. Factories able to mass produce were being built all over Europe and the Western world. Cities saw massive growth as people from the countryside came looking for work. This was reflected in the modernist movements in art at the time, as artists who saw a rapid change in the world attempted to express this change in the avant-garde. The first world war went a long way to changing peoples attitudes towards modernity, as the capabilities of the machine and mass production took on a sinister role, causing death in unimaginable quantities.

Generally nowadays it means to bring things up to date with the technology and fashion of the present day.