Explanation

Step 1: Create a YAML file.
If your AKS cluster is RBAC-enabled, you must create a service account and role binding for use with Tiller.
To create a service account and role binding, create a file named rbac-virtual-kubelet.yaml Step 2: Run kubectl apply.
Apply the service account and binding with kubectl apply and specify your rbac-virtual-kubelet.yaml file.
Step 3: Run helm init.
Configure Helm to use the tiller service account:
helm init --service-account tiller
You can now continue to installing the Virtual Kubelet into your AKS cluster.
References: https://docs.microsoft.com/en-us/azure/aks/virtual-kubelet

Explanation
To build your code or deploy your software using Azure Pipelines, you need at least one agent.
If your on-premises environments do not have connectivity to a Microsoft-hosted agent pool (which is typically the case due to intermediate firewalls), you'll need to manually configure a self-hosted agent on on-premises computer(s). The agents must have connectivity to the target on-premises environments, and access to the Internet to connect to Azure Pipelines or Team Foundation Server.
References:
https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/agents?view=azure-devops

Explanation

Box 1: Progressive exposure
Continuous Delivery may sequence multiple deployment "rings" for progressive exposure (also known as
"controlling the blast radius"). Progressive exposure groups users who get to try new releases to monitor their experience in "rings." The first deployment ring is often a "canary" used to test new versions in production before a broader rollout. CD automates deployment from one ring to the next and may optionally depend on an approval step, in which a decision maker signs off on the changes electronically. CD may create an auditable record of the approval in order to satisfy regulatory procedures or other control objectives.

Box 2: Feature flags
Feature flags support a customer-first DevOps mindset, to enable (expose) and disable (hide) features in a solution, even before they are complete and ready for release.
Box 3: Blue/green
Blue/green deployments which means that instead of replacing the previous version (here we refer to this version as blue), we bring up the new version (here referred to as the green version) next to the existing version, but not expose it to the actual users right away. On the condition of having successfully validated that the green version works correctly, we will promote this version to the public version by changing the routing configuration without downtime. If something is wrong with the green version we can revert back without users every noticing interruptions.
Reference:
https://docs.microsoft.com/en-us/azure/devops/learn/what-is-continuous-delivery
https://docs.microsoft.com/en-us/azure/devops/migrate/phase-features-with-feature-flags
https://medium.com/@denniszielke/continuous-kubernetes-blue-green-deployments-on-azure-using-nginx-appga

Explanation
Topic branches, however, are useful in projects of any size. A topic branch is a short-lived branch that you create and use for a single particular feature or related work. This is something you've likely never done with a VCS before because it's generally too expensive to create and merge branches. But in Git it's common to create, work on, merge, and delete branches several times a day.
Reference:
https://git-scm.com/book/en/v2/Git-Branching-Branching-Workflows

Explanation
System-assigned managed identities enable Azure resources to authenticate to cloud services without storing credentials in code. They also support granting privileges to the identity, making them the ideal choice for this scenario. Source: Microsoft