In this thesis, we address major challenges in searching temporal document collections. In such collections, documents are created and/or edited over time. Examples of temporal document collections are web archives, news archives, blogs, personal emails and enterprise documents. Unfortunately, traditional IR approaches based on termmatching only can give unsatisfactory results when searching temporal document collections. The reason for this is twofold: the contents of documents are strongly time-dependent, i.e., documents are about events happened at particular time periods, and a query representing an information need can be time-dependent as well, i.e., a temporal query. On the other hand, time-only-based methods fall short when it comes to reasoning about events in social media. During the last few years users create chronologically ordered documents about topics that draw their attention in an ever increasing pace. However, with the vast adoption of social media, new types of marketing campaigns have been developed in order to promote content, i.e. brands, products, celebrities, etc
