Dogecoin is a cryptocurrency with a focus on fun, generosity, and community. It is unlike many other blockchain projects in that it does not aim to solve any ambitious problems. Dogecoin was originally created as a meme coin and has gained a large following that use the coin (DOGE) as an internet tipping and fundraising system.
Although Dogecoin was first created as somewhat of a joke, it has a passionate community that has used the platform for a variety of purposes. The project has gained widespread publicity and DOGE is traded on many exchanges.

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Decred (DCR) is a decentralized currency with an emphasis on community based governance. Decred is led by several early adopters of Bitcoin and is designed to implement many of the goals of early Bitcoin idealists. Decred is highly focused on community contribution and governance. Users that contribute to the community can receive compensation for their work and anybody can submit a proposal ti make an improvement to the platform.
Decred has a hybrid Proof-of-Activity (PAC) consensus algorithm that combines the mining of Proof-of-Work (PoW) with the stake verifying model of Proof-of-Stake (PoS). It's designed to incentivize the community to participate and to reward both miners and stake verifiers. When DCR is mined, PoW miners receives 60% of the coins, PoS voters receive 30%, and 10% goes towards the development of the Decred platform.

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Ripple is a real-time settlement and remittance network that is designed for the banking industry. Its settlement infrastructure technology has been adopted by a growing list of financial institutions looking to leverage the benefits of distributed ledgers. Ripple's real-time settlement network connects banks and enables cross border settlements and transactions in real-time. The current settlement infrastructure requires many intermediaries, and performing transactions take time and cost money. Ripple provides the underlying infrastructure for banks, and enables these transactions to be executed directly at almost no cost.