Bitcoin in the context of "Cryptocurrency"

Electronic waste (or e-waste) describes discarded electrical or electronic devices. It is also commonly known as waste electrical and electronic equipment (WEEE) or end-of-life (EOL) electronics. Used electronics which are destined for refurbishment, reuse, resale, salvage recycling through material recovery, or disposal are also considered e-waste. Informal processing of e-waste in developing countries can lead to adverse human health effects and environmental pollution. The growing consumption of electronic goods due to the Digital Revolution and innovations in science and technology, such as bitcoin, has led to a global e-waste problem and hazard. The rapid exponential increase of e-waste is due to frequent new model releases and unnecessary purchases of electrical and electronic equipment (EEE), short innovation cycles and low recycling rates, and a drop in the average life span of computers.

Electronic scrap components, such as CPUs, contain potentially harmful materials such as lead, cadmium, beryllium, or brominated flame retardants. Recycling and disposal of e-waste may involve significant risk to the health of workers and their communities.

A central bank digital currency (CBDC) is a digital version of a country's official currency, created by the nation's central bank rather than by private companies. Unlike cryptocurrencies such as Bitcoin, CBDCs are issued by a state and may work alongside physical cash. As of 2024, the Bahamas, Jamaica, and Nigeria have launched CBDCs, and 134 countries are researching their own versions while other jurisdictions, such as Florida, have banned CBDCs citing privacy concerns.

CBDCs could enable faster, cheaper payments and improve financial inclusion, but raise concerns about privacy and the potential for them to be used as a "tool for coercion and control". CBDC implementation could affect banks' financial stability, requiring careful policy design.

Ransomware is a type of malware that encrypts the victim's personal data until a ransom is paid. Difficult-to-trace digital currencies such as paysafecard or Bitcoin and other cryptocurrencies are commonly used for the ransoms, making tracing and prosecuting the perpetrators difficult. Sometimes the original files can be retrieved without paying the ransom due to implementation mistakes, leaked cryptographic keys or a complete lack of encryption in the ransomware.

Ransomware attacks are typically carried out using a Trojan disguised as a legitimate file that the user is tricked into downloading or opening when it arrives as an email attachment. However, one high-profile example, the WannaCry worm, traveled automatically between computers without user interaction.

Proof of work (also written as proof-of-work, an abbreviated PoW) is a form of cryptographic proof in which one party (the prover) proves to others (the verifiers) that a certain amount of a specific computational effort has been expended. Verifiers can subsequently confirm this expenditure with minimal effort on their part. The concept was first proposed by Moni Naor and Cynthia Dwork in 1993 as a way to deter denial-of-service attacks and other service abuses such as spam on a network by requiring some work from a service requester, usually meaning processing time by a computer. Extending the work of Cynthia Dwork and Moni Naor, Adam Back formally described a proof of work system called Hashcash as a protection against email spam in 1997. The term "proof of work" was first coined and formalized in a 1999 paper by Markus Jakobsson and Ari Juels. The concept was adapted to digital tokens by Hal Finney in 2004 through the idea of "reusable proof of work" using the 160-bit secure hash algorithm 1 (SHA-1).

Proof of work was later popularized by Bitcoin as a foundation for consensus in a permissionless decentralized network, in which miners compete to append blocks and mine new currency, each miner experiencing a success probability proportional to the computational effort expended. PoW and PoS (proof of stake) remain the two best known Sybil deterrence mechanisms. In the context of cryptocurrencies they are the most common mechanisms.

Alternative finance refers to financial channels, processes, and instruments that have emerged outside of the traditional finance system, such as regulated banks and capital markets. Examples of alternative financing activities through 'online marketplaces' are reward-based crowdfunding, equity crowdfunding, revenue-based financing, online lenders, peer-to-peer consumer and business lending, and invoice trading third party payment platforms.

Alternative finance instruments include cryptocurrencies such as Bitcoin, SME mini-bond, social impact bond, community shares, private placement and other 'shadow banking' mechanisms. Alternative finance differs to traditional banking or capital market finance through technology-enabled 'disintermediation', which means utilising third party capital by connecting fundraisers directly with funders, in turn, reducing transaction costs and improving market efficiency.