As known, blockchains are traditionally blind to the real world. This implies the reliance on third parties called oracles when extrinsic data is needed for smart contracts. However, reintroducing trust and single point of failure, oracles implementation is still controversial and debated. The blindness to the real world makes blockchains also unable to communicate with each other preventing any form of interoperability. An early approach to the interoperability issue is constituted by wrapped tokens, representing blockchain native tokens issued on a non-native blockchain. Similar to how oracles reintroduce trust, and single point of failure, the issuance of wrapped tokens involves third parties whose characteristics need to be considered when evaluating the advantages of crossing-chains. This paper provides an overview of the wrapped tokens and the main technologies implemented in their issuance. Advantages, as well as limitations, are also listed and discussed.Comment: 14 pages, 4 figures and 1 table. Oriented to a conference