In this paper we present an overview of different semantic-based approaches to matchmaking and negotiation in electronic markets, showing how semantics can lead to a new generation of EC systems. We will introduce and briefly review different solutions to solve the two problems in the context of search/retrieval, multiattribute auctions, advertising, just to cite a few, showing the added-value provided by these techniques in so lively environments. The presentation range from strictly semantic-based approaches, to those combining logic languages with utility theory, to most recent ones relying on Semantic Web technologies and Linked Data datasets.