ICP Fundamentals

The Internet Computer is a platform that hosts a large number of applications, all of those applications run smoothly within special containers called canisters.

The Motoko language places a strong emphasis on types and is more strict in enforcing them compared to other general-purpose languages like JavaScript or Python. This strictness serves a purpose, as it helps prevent errors and issues.

Primitive types are fundamental core data types that are not composed of more fundamental types. Primitive types are all the types that do not need to be imported before they can be used in type annotation.

Candid is an IDL describing the public services deployed in canisters on the Internet Computer. The Candid interface allows inter-operation between services, and between services and frontends, independently of the programming language used.

Modules are collections of named variables, functions, and types, each designed for a specific purpose. They help us organize our code efficiently. Typically, a module resides in its own file, allowing us to import its contents into other Motoko files as needed.

In Motoko, arrays have a fixed size that is determined when the array is created. This means that the size cannot be increased later on. To add a new element to an array, a new array must be created and all of the existing elements must be transferred to the new array manually.

Similar to other variables in Motoko, objects can be mutable or immutable. The object we've just defined is immutable, once the fields have been assigned a value they cannot be modified.

Motoko throws an error because null is not of type Nat. To indicate that a function may return either a Nat value or null, we need a way to express that the function's return type can be one of two possibilities.

In Motoko, error handling can be a bit confusing, especially if you are used to error handling in other programming languages. 

To achieve the vision of the Internet Computer, services (i.e canisters) needs to be able to call each other and run in an interoperable way. This capability is achieved through inter-canister calls. In this lesson, we will see how we can realize such calls and the potential issues to avoid.

When a canister is upgraded, the state is lost by default. This means all data application data will be lost, unless it's handled to persist when the canister is upgraded.

Canisters are hosted and executed by nodes that participate in the IC consensus However, those nodes are not directly accessible by end users.

Throughout history, humans have found different creative ways to organize in social groups and structures. They have done so for different reasons such as safety, support, social identity, work, power or even economics.

The most developed DAO operating on the IC is the one that manages the network itself. This DAO is called the Network Nervous System and it is responsible for making decisions about the future of the network, coordinating various parties, and arranging the network's structure.