Since I study interaction design I get asked on a daily base what an interaction designer does so this is +- the evolution of my answers I found:

• in interaction design bachelor you go from technological stuff like programming a game, web, apps, to also do animations in 3d, to also create reactive screens, interactive object experiences, basically everything design has to offer.
• everything that has to do with design, interaction, technology etc.
• I design interactions (which is what I will answer from now on)

Interpretation of interaction design:

• designing interactions
• designing for interactions
• creating experiences
• connecting design and technology

Each interaction designer has his own view and interpretation of what interaction design is and all of them are correct, because it's a very diverse job.

Ways of interactions:

computer <> computer

human <> computer

human <> human

human <> environment

environment <> environment

human <> non-living thing