Bittrex is a Seattle, U.S. based and regulated exchange. It offers several trading pairs and supports more than 190 cryptocurrencies. It offers speedy transactions, high stability, and follows some risk management practices. Bittrex’s fees are .25%, which are somewhat high compared to their competition. Bittrex’s customer support is pretty good and uses Slack, Twitter and Email.
Darknet markets present challenges in regard to legality. Bitcoins and other forms of cryptocurrency used in dark markets are not clearly or legally classified in almost all parts of the world. In the U.S., bitcoins are labelled as "virtual assets". This type of ambiguous classification puts pressure on law enforcement agencies around the world to adapt to the shifting drug trade of dark markets.[76]
Taking the first option listed above, which is to buy the underlying, you become the direct holder of the digital asset. Upon purchase, the cryptocurrency is sent to your bitcoin address or account (wallet) with the exchange. From there, you can transfer the crypotocurrency to any bitcoin address or wallet address using your private key that verifies you control ownership of the asset.
The creators of digital currencies are often independent of the digital currency exchange that facilitate trading in the currency.[3] In one type of system, digital currency providers (DCP) are businesses that keep and administer accounts for their customers, but generally do not issue digital currency to those customers directly.[1][5] Customers buy or sell digital currency from digital currency exchanges, who transfer the digital currency into or out of the customer's DCP account.[5] Some exchanges are subsidiaries of DCP, but many are legally independent businesses.[1] The denomination of funds kept in DCP accounts may be of a real or fictitious currency.[5]
Like Bitcoin, Dash is meant to be used as a digital currency but has some added values such as much faster transaction times and lower fees. For a slightly higher fee, Dash has the added function of “instant send” which allows transactions to be confirmed almost instantly. This is one of the main selling points of Dash because many believe that this feature would allow it to be used in brick and mortar establishments.

NEM — Unlike most other cryptocurrencies that utilize a Proof of Work algorithm, it uses Proof of Importance, which requires users to already possess certain amounts of coins in order to be able to get new ones. It encourages users to spend their funds and tracks the transactions to determine how important a particular user is to the overall NEM network.

Aus meiner Sicht besonders spannend sind die Kapitel zu den weiteren Anwendungsmöglichkeiten, die sich aus dem Blockchain-Konzept für ein "automatisiertes Vertrauen" ergeben. Die Konsequenz, darüber nachzudenken, wofür wir in Zukunft Vertrauensvolle (zentrale) Instanzen benötigen und wo und wie wir Vertrauen algorithmisch (dezentral) abbilden können, finde ich absolut faszinierend. Es geht also nicht nur bei Banken und in der Finanzwelt um die Fragen „zentral oder dezentral“, „Torwächter oder Macht“, sondern auch in vielen anderen Branchen. - Eine absolute Leseempfehlung!

Pundi X originates in Indonesia, and while cryptocurrency exchanges are permitted, cryptocurrency payments for goods and services are currently banned by the government. Pundi X is able to deploy their hardware without breaking the law because their POS system defaults to accepting payments from non-cryptocurrency systems, like bank cards and Apple Pay.
Cryptocurrencies are a potential tool to evade economic sanctions for example against Russia, Iran, or Venezuela. In April 2018, Russian and Iranian economic representatives met to discuss how to bypass the global SWIFT system through decentralized blockchain technology.[56] Russia also secretly supported Venezuela with the creation of the petro (El Petro), a national cryptocurrency initiated by the Maduro government to obtain valuable oil revenues by circumventing US sanctions.
The proof-of-stake is a method of securing a cryptocurrency network and achieving distributed consensus through requesting users to show ownership of a certain amount of currency. It is different from proof-of-work systems that run difficult hashing algorithms to validate electronic transactions. The scheme is largely dependent on the coin, and there's currently no standard form of it. Some cryptocurrencies use a combined proof-of-work/proof-of-stake scheme.[16]