Expressing the information need for search formulation and executing the query is the starting point of a search process [13]. Search formulation includes the articulation of search terms and the use of search operators if there are any. It also includes the search tactics used for reaching the search goal. The choice of search terms is a reflection of the searcher’s understanding of her information need, what is insufficient in her knowledge structure. In practice, a searcher expresses her information need by selecting search terms and search tactics, that is, by formulating and reformulating queries. The learning process required for selecting terms and tactics depends at least on the searcher’s level of knowledge on the search topic and system, and it is influenced also by the information provided in the search results [14] and the support tools incorporated in the search interface [15, 16]. The searcher probably reflects and reforms her understanding of the topic, and consequently on terms for querying.