**2. Literature review**

## **2.1 Destinations**

A tourism destination is "a group of actors linked by mutual relationships with specific rules, where the action of each actor influences those of the others so that common objectives must be defined and attained in a coordinated way" ([13], p. 23). Destinations have been conceptualized as formal or informal networks of actors [14] or clusters [15], defined by Porter ([16], p. 197–198) as "geographic concentrations of interconnected companies, specialized suppliers, service providers, firms in related industries, and associated institutions (e.g., universities, standards agencies, and trade associations) in particular fields that compete but also cooperate". In order to understand learning processes in tourism destinations getting a sustainability certification, we, therefore, build on previous studies that address learning in clusters, understand clusters in tourism as learning systems [8, 17–19] as well as studies applying organizational learning theory to understand innovation and development [9].
