> For the complete documentation index, see [llms.txt](https://docs.applayer.com/testnet/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.applayer.com/testnet/introducing-applayer/a-primer-on-smart-contracts.md). # A Primer on Smart Contracts In the field of cryptocurrencies, *smart contracts* are pieces of code that can run on a blockchain and enforce certain rules or logic, much like real-world contracts. However, due to the inherent programmability provided by blockchain technology, smart contracts can go much further than that, acting as a foundation to build decentralized applications and concepts such as DeFi, while eliminating the necessity of "trust" usually provided by a third-party on a traditional real-world contract. Although a fairly old concept in theory, smart contracts in practice have been popularized by the [Ethereum](https://ethereum.org) blockchain and its implementation of a virtual machine - the "Ethereum Virtual Machine", or [EVM](https://ethereum.org/en/developers/docs/evm) - that made it possible to deploy and interact with them. Other coins such as [Avalanche](https://support.avax.network/en/articles/5417030-what-is-the-ethereum-virtual-machine-evm), [Tron](https://developers.tron.network/v4.4.2/docs/tvm) and [Bitcoin Cash](https://cashscript.org/) have followed along with their own implementations as time went on. [Ethereum's website](https://ethereum.org/en/smart-contracts/) has a good explanation of smart contracts in EVM and most major scaling solutions for Ethereum use the same unsustainable technology, introducing the same issues of scalability in every deployed layer. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.applayer.com/testnet/introducing-applayer/a-primer-on-smart-contracts.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.