Electronica is an umbrella term and has been diluted to the point of being shorthand for electronic music. Any style of electronic music can be considered electronica. In some regions like the UK it is synonymous with IDM as it started in the early 1990s as a term to describe a strain of artsy and lush EDM intended to be listened to and not danced to or found in a club setting. By the mid 1990s however American pop artists began to be lumped with the term and it was changed to mean any electronic music with the potential for pop appeal. By the 2000s the term lost any concrete meaning and is virtually identical to saying electronic music.
Due to the terms vagueness many such as Ishkur of Ishkur's guide to electronic music have criticized it as being virtually useless.