As it will be shown in section II, the key notion of context
may have multiple interpretations in Information Retrieval (IR).
It may be related to the characteristics and preferences of a
specific user or group of users (in this case contextualization
can be referred to as personalization), or it may be related to
user geographic localization (when for example using a search
engine on a smart-phone), or it may refer to the information that
qualifies the content of a given document/web page (for
example its author, its creation date, its format etc.).
The development and increasing use of tools that either help
users to express their topical preferences, or automatically