Are there any restrictions when defining your own generic template?

When defining your own generic templates in C#, there are some restrictions:

• Parameter types must be reference types, value types, or have certain constraints, such as inheriting from a specific class, implementing an interface, or having a parameterless constructor.
• Primitive types cannot be used directly without constraints if specific functionality is required.
• You cannot instantiate a type parameter without the 'new()' constraint, as the compiler does not know how to initialize it.
• You cannot use operators like typeof(T) or is T without constraints.

Example of a constraint:

public class Repository<T> where T : IEntity, new()
{
    public T CreateNew() => new T();
}

Here, T must implement the IEntity interface and have a parameterless constructor.