Artifacts are the logs, documentation, and other materials needed for audits and compliance; they are the evidence to support compliance activities. Both providers and customers have responsibilities for producing and managing their respective artifacts.
Reference: CSA Security GuidelinesV.4(reproduced here for the educational purpose)

The characteristics of cloud computing are
1. 0n-demand self-service: A consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with each service provider.
2. Broad network access: Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms(e.g, mobile phones, tablets, laptops and workstations).
3. Resource pooling: The provider's computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. There is a sense of location independence in that the customer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction(e.g, country, state or datacenter).
Examples of resources include storage, processing, memory and network bandwidth.
4. Rapid elasticity: Capabilities can be elastically provisioned and released, in some cases automatically, to scale rapidly outward and inward commensurate with demand. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be appropriated in any quantity at anytime.
5. Measured service: Cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service(e.g, storage, processing, bandwidth and active user accounts).
Resource usage can be monitored, controlled and reported, providing transparency for the provider and consumer.

Containers are code execution environments that run within an operating system(for now), sharing and leveraging resources of that operating system. While a VM is a full abstraction of an operating system, a container is a constrained place to run segregated processes while still utilizing the kernel and other capabilities of the base 0S.
Ref: CSA Security Guidelines V4.0