The paper provides an overview of the work performed by the authors since the year 2000 in the field of runtime verification. Runtime verification is the discipline of analyzing program/system executions using rigorous methods. The discipline covers such topics as specification-based monitoring, where single executions are checked against formal specifications; predictive runtime analysis, where properties about a system are predicted/inferred from single (good) executions; fault protection, where monitors actively protect a running system against errors; specification mining from execution traces; visualization of execution traces; and to be fully general: computation of any interesting information from execution traces. The paper attempts to draw lessons learned from this work, and to project expectations for the future of the field.