**7. Conclusions**

While the authors of these articles discussed the multifaceted features of GAGs, they are all well motivated by specific applications in biology and medicine and will develop appropriate tools that are likely to be important in structuring a large amount of available data and opening the field to cross-disciplinary endeavors. We hope that these articles will not only provide timely case studies but that they will also form the basis of a series of questions aimed at answering the broader question of what remains to be solved about GAGs?

**Funding:** Mentioned research by S.P. profited from Campus Rhodanien Co-Funds (https://unigecofunds.ch/alliance-campus-rhodanien, accessed on 11 March 2021) support from ANR PIA Glyco@Alps [ANR-15-IDEX-02]; Alliance), and Labex Arcane/CBH-EUR-GS [ANR-17-EURE-0003]. Innogly COST Action covered the costs of the meeting where the Special issue was inaugurated. D.N. was partially funded by the Research Committee of University of Crete (ELKE), grant number (KA:10028).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** This article is part of the Innogly Cost action initiative.

**Conflicts of Interest:** The authors declare no conflict of interest.
