Ethereum has become reliable for its community of users, developers, and businesses, meaning that participants trust it to function as intended. This reliability is the result of its open-source codebase, widespread network of participants and contributors, and the ability for anyone to review applications before interacting with them.
Since its launch, Ethereum has consistently provided high availability, with little to no downtime. This tenure of uptime speaks to the network's lack of reliance on any one party and its ability to defend and/or discourage outside attacks. Ethereum has thousands of supporting nodes and validators who ensure that the system continues to function as designed without discrimination, censorship, or manipulation.
Ethereum's open-source codebase also contributes to its reliability. By making its code publicly accessible, developers and users can audit and verify its logic and test its outcomes. This helps to identify and address vulnerabilities before they can become significant issues.
Additionally, every application, or even transaction, on Ethereum can be fully reviewed by anyone before interacting with it. This openness allows users to verify the code before spending funds, giving them assurance in the services they choose to engage with. By enabling users to understand how applications work, Ethereum encourages accountability among contributing projects and development teams compared to traditional closed systems that do not face the same level of public scrutiny.