This online tool can be used for a wide variety of annotation tasks, including visualization and collaboration.
brat is designed in particular for structured annotation, where the notes are not freeform text but have a fixed form that can be automatically processed and "interpreted" by a computer. brat also supports the annotation of n-ary associations that can link together any number of other annotations participating in specific roles. brat also implements a number of features relying on natural language processing techniques to support human annotation efforts.
Other applications include entity mention detection, event extraction, coreference resolution, chunking, dependency syntax, meta-knowledge, and corpora annotation.