Abstract : Social tagging systems have recently became very pop- ular as a means to classify large sets of resources shared among on-line communities. However, the folksonomies re- sulting from the use of these systems revealed limitations : tags are ambiguous and their spelling may vary, and folk- sonomies are difficult to exploit in order to retrieve or ex- change information. This article compares the recent at- tempts to overcome these limitations and to support the use of folksonomies with formal languages and ontologies from the Semantic Web.
