What is a suku?

Could you please elaborate on the concept of a suku? I understand it's related to Islamic finance, but I'm not entirely clear on its specific nature and purpose. Is it a type of financial instrument or a principle? How does it differ from conventional financial products? And what are the benefits and risks associated with investing in sukuk? I'm particularly interested in understanding how it aligns with Islamic principles and how it's been adopted in the global financial market.