1. A user interface system for exploratory search and media discovery programmed for organizing media items in a data space and making these media items navigable by users, the user interface system comprising a processing unit and a display unit, the display unit displaying a specific rigid 2-dimensional geometrical grid with a focal field in a center of the grid, the focal field being surrounded by at least one closed rectangular ring or by a plurality of closed rectangular rings getting repeatedly smaller towards the outside, where each ring is subdivided regularly into rectangular fields, resulting in the geometrical grid that subdivides any rectangular display in a regular, symmetric and centric manner as a recursive tiling, where this specific grid is used to visualize relations between the media items placed in the focal field and related media items distributed in the fields surrounding the focal field, following a focus-plus-context principle, where the media item in the focal field is the focus and the surrounding items are the context, from which users can select any item to become the new focus, the processing unit being programmed to filter and to map media items from n-dimensional data spaces to the specific grid, as a focus-plus-context visualization that serves as a user interface for enabling a semantically coherent navigation flow, where the user selects any media item of the user's interest from the context, and by that defines it as the new focus, which triggers queries to retrieve related media items, which are mapped again to the grid building an updated context, from where the user again selects a media item triggering new queries and consequently updated display of focus plus context, the processing unit being programmed to perform a dimension reduction of the n-dimensional data structure for mapping media items to the fields of the specific grid so that the proximity to the focus visualizes a degree of relevance of each context item to the item in the focus, and the arrangement along the grid's directions is an order by similarities.