Bitcoin and other prominent cryptocurrencies have gained much attention since the last several years. Globally known as digital coin and virtual currency, this cryptocurrency is gained and traded within the blockchain system. The blockchain technology adopted in using the cryptocurrency has raised the eyebrows within the banking sector, government, stakeholders and individual investors. The rise of the cryptocurrency within this decade since the inception of Bitcoin in 2009 has taken the market by storm. Cryptocurrency is anticipated as the future currency that might replace the current paper currency worldwide. Even though the interest has caught the attention of users, many are not aware of its opportunities, drawbacks and challenges for the future. Researches on cryptocurrencies are still lacking and still at its infancy stage. In providing substantial guide and view to the academic field and users, this paper will discuss the opportunities in the cryptocurrency such as the security of its technology, low transaction cost and high investment return. The originality of this paper is on the discussion within law and regulation, high energy consumption, possibility of crash and bubble, and attacks on network. The future undertakings of cryptocurrency and its application will be systematically reviewed in this paper.

Abstract
1. Introduction
    1.1. Background and History
    1.2. Mining and the Blockchain System
2. Critics of Cryptocurrency
    2.1. Opportunities and Advantages
    2.2. Challenges
3. Discussion
4. Improvement and Future Work onCryptocurrencies
5. Conclusion
References

• Muhammad Ashraf FAUZI(Faculty of Industrial Management, Universiti Malaysia Pahang)
• Norazha PAIMAN(Centre for Liberal Studies, Universiti Kebangsaan Malaysia) Corresponding Author
• Zarina OTHMAN(Centre for Liberal Studies, Universiti Kebangsaan Malaysia)