With increased trend toward digitization and inter-connectivity  in the modern world, a new class of problems have emerged related to the tracking and management of digitized assets.  At the most simple case, tracking the transfer of money between users occurs through verification and interaction with centralized third parties.  The centralization creates concerns for privacy and censorship and therefore research into new alternatives has gained traction.  One area of research is Distributed Ledger Technologies which use distributed networks and consensus mechanisms to perform the the same functionality in a secure manner without the need of trusted and centralized entities.  Blockchain, and more recently Directed Acyclic Graph, based solutions are an area that has been seen increased interest since 2009.  The potential for these technologies expands beyond simple currency transactions between parties to include programmable aspects and ownership tracking of other physical assets.
This research attempts to consolidate some of the recent research efforts in this field into a single and complete source of reference for researchers interested in this space.  An analysis of research focused on the methods to achieve consensus, security aspects, use cases vulnerabilities are consolidated and reviewed into this comprehensive survey paper.