Overview of semantic indexing and question answering in the biomedical domain. The BIOASQ challenge focuses in pushing systems towards implementing pipelines that can realize the workflow shown in the figure. Starting with a variety of data sources (lower right corner of the figure), semantic indexing and integration brings the data into a form that can be used to respond effectively to domain specific questions. A semantic QA system associates ontology concepts with each question and uses the semantic index of the data to retrieve the relevant pieces of information. The retrieved information is then turned into a concise user-understandable form, which may be, for example, a ranked list of candidate answers (e.g., in factoid questions, like “What are the physiological manifestations of disorder Y?”) or a collection of text snippets, ideally forming a coherent summary (e.g., in “What is known about the metabolism of drug Z?”). The figure also illustrates how these steps are mapped to the BIOASQ challenge tasks. With blue, Task 1a is depicted, while red depicts Task 1b.