3M's of Multi-Species Biofilms: Microbial Pathogens, Microenvironments and Minimalist Laboratory Approaches to Study Multi-Species Biofilms under Microenvironmental Conditions -- Methods for the visualization of multispecies biofilms -- In vitro, in vivo and ex vivo models to study mixed bacterial and fungal biofilms -- Current and emerging in vitro and in vivo biofilm models in investigating fungal-bacterial polymicrobial communities: Fungal-bacterial biofilm models -- Involvement of bacterial outer membrane vesicles in cell-cell interactions and their role in multi-species communities -- Polymicrobial biofilm models: the case of periodontal disease as an example -- Polymicrobial biofilms in cystic fibrosis lung infections: effects on antimicrobial susceptibility -- High resolution methods to study microbial interactions in biofilms -- Unity in Diversity: Interkingdom Polymicrobial Biofilms in Disease.