Wildfire is not only the most important natural disturbance for forests and other vegetation ecosystems on Earth, but also a major natural disaster for human society. In turn, human activities have profound interaction with the occurrence and distribution of wildfires. Wildfire has become one of the key issues in the studies of global change and its environmental impacts. Based on a thorough analysis of the international literature on wildfire, this paper reviews the progresses in wildfire study from the beginning of the 21^st century in terms of the techniques of wildfire detection, assessment and early warning, spatiotemporal patterns characterization, the impacts of climate changes and human activities on wildfires, and the environmental-ecological-evolutionary outcomes of wildfires. In summary, significant improvements have been made in the spatial and temporal resolutions of wildfire observation and fire characterization has advanced from a burned-area centered approach to multiple indicators with an emphasis on comprehensive characterization of fire regime. Climate change has significantly affected the frequency of wildfire occurrences in certain regions. Global warming is expected to further amplify wildfire risk, which has attracted increasing concerns over the mechanisms and the ecological consequences of extreme mega-fires. On the one hand, human causes increase the wildfire frequency by creating ignition sources; on the other hand, human interferences inhibit wildfire occurrence by enhancing ecosystem management intensity, fire-fighting, and reducing fuel connectivity. Over the history, vegetation has evolved with the presence of wildfires and has thus developed a series of fire adaptation mechanisms. Such fire-relevant functional traits affect ecosystem responses to wildfire and are valuable in guiding post-fire ecological restoration and reconstruction. We conclude that future wildfire research should be directed towards across-scale fire detection and mapping with multiple techniques, data-model fusion between observations and wildfire simulation in dynamic vegetation models and a combination between fine-scale mechanism characterization and large-scale fire impact assessment.