In this new information age, where information, thoughts and opinions are shared so prolifically through online social networks, tools that can make sense of the content of these networks are paramount. In order to make best use of this information, we need to be able to distinguish what is important and interesting, and how this relates to what is already known. Social web analysis is all about the users who are actively engaged and generate content. This content is dynamic, rapidly changing to reflect the societal and sentimental fluctuations of the authors as well as the ever-changing use of language. While tools are available for information extraction from more formal text such as news reports, social media affords particular challenges to knowledge acquisition, such as multilinguality not only across but within documents, varying quality of the text itself (e.g. poor grammar, spelling, capitalisation, use of colloquialisms etc), and greater heterogeneity of data. The analysis of non-textual multimedia information such as images and video offers its own set of challenges, not least because of its sheer volume and diversity. The structuring of this information requires the normalization of this variability by e.g. the adoption of canonical forms for the representation of entities, and a certain amount of linguistic categorization of their alternative forms.
Due to the reasons described above, data and knowledge extracted from social media often suffers from varying, non-optimal quality, noise, inaccuracies, redundancies as well as inconsistencies. In addition, it usually lacks sufficient descriptiveness, usually consisting of labelled and, at most, classified entities, which leads to ambiguities.
This calls for a range of specific strategies and techniques to consolidate, enrich, disambiguate and interlink extracted data. This in particular benefits from taking advantage of existing knowledge, such as Linked Open Data, to compensate for and remedy degraded information. A range of techniques are exploited in this area, for instance, the use of linguistic and similarity-based clustering techniques or the exploitation of reference datasets. Both domain-specific and cross-domain datasets such as DBpedia or Freebase can be used to enrich, interlink and disambiguate data. However, case- and content-specific evaluations of quality and performance of such approaches are missing, hindering the wider deployment. This is of particular concern, since data consolidation techniques involve a range of partially disparate scientific topics (e.g. graph analysis, data mining and interlinking, clustering, machine learning), but need to be applied as part of coherent workflows to deliver satisfactory results.