  Single-molecule F\"{o}rster resonance energy transfer (smFRET) has become a
mainstream technique for probing biomolecular structural dynamics. The rapid
and wide adoption of the technique by an ever-increasing number of groups has
generated many improvements and variations in the technique itself, in methods
for sample preparation and characterization, in analysis of the data from such
experiments, and in analysis codes and algorithms. Recently, several labs that
employ smFRET have joined forces to try to bring the smFRET community together
in adopting a consensus on how to perform experiments and analyze results for
achieving quantitative structural information. These recent efforts include
multi-lab blind-tests to assess the accuracy and precision of smFRET between
different labs using different procedures, the formal assembly of the FRET
community and development of smFRET procedures to be considered for entries in
the wwPDB. Here we delve into the different approaches and viewpoints in the
field. This position paper describes the current "state-of-the field", points
to unresolved methodological issues for quantitative structural studies,
provides a set of 'soft recommendations' about which an emerging consensus
exists, and a list of resources that are openly available. To make further
progress, we strongly encourage 'open science' practices. We hope that this
position paper will provide a roadmap for newcomers to the field, as well as a
reference for seasoned practitioners.
