Containers

• Containers offer the same abilities as a Virtual Machine but with less overhead.
• Containers do not virtualize a complete OS

Used for

• Software Portability -- Running software consistentyl on different machines
• Isolation -- Keeping individual pieces of software separate from one another
• Scaling -- Increasing or decreasing resource sallocated to software as needed
• Automation -- Automating processes to save time and money
• Efficient Resources Usage -- Containers use resources efficiently, which saves money

Advantages

• Isolation and portability of VMs
• More lightweight thean VMs - Less resources usage
• Faster than VMs -- Container can start in seconds
• Smaller than VMs -- Container images canb e measured in megabutes, not gigabytes

Limitations

• Less flexible than VMs -- You can't run a Windows container on a Linux machine.
• Introduces new challenges around orchestration and automation

Docker

• A container runtime, which actually allows you to implement container. (Container is just a concept)
• Allows you to build and manage containers and container images

Other Container Runtimes

• rkt
  • Ultimately does the same thing as Docker.
  • Is more linux like and may be easier for linux stuff
  • Supports more container images formats than Docker
• containerd
  • Emphasizes simplicity, robustness, portability
  • Focused solely on running containers
  • Does not has many features as Docker but may not be a downside