The standby instance is used in high availability to replace the primary instance when failover occurs. The standby instance doesn't appear in the Google Cloud Console. When failover occurs, connections to the primary instance are automatically transferred to the standby instance.
Cloud SQL Key Terms:
Cloud SQL instance
A Cloud SQL instance corresponds to one virtual machine (VM). The VM includes the database instance and accompanying software containers to keep the database instance up and running.
Database instance
A database instance is the set of software and files that operate the databases: MySQL, PostgreSQL or SQL Server.
High availability
Cloud SQL instances using high availability (HA) provide greater reliability than non-HA instances.
HA in Cloud SQL works by having two synchronized instances: a primary instance and a standby instance. Each instance has exactly one VM. Each instance is in a different zone in the same region.
Failover
A failover is when Cloud SQL switches serving from the original primary instance to the standby instance.
Autofailover is a mechanism that automatically triggers failover when a Cloud SQL instance didn't issue a heartbeat in the previous interval.
Standby instances
The standby instance is used in high availability to replace the primary instance when failover occurs. The standby instance doesn't appear in the Google Cloud Console. When failover occurs, connections to the primary instance are automatically transferred to the standby instance.
Clone
When you clone a Cloud SQL instance, you create a new instance that is a copy of the source instance, but is completely independent. After cloning is complete, changes to the source instance are not reflected in the clone, and changes in the clone are not reflected in the source instance.
Replication
Replication is the ability to create copies of a Cloud SQL instance or an on-premises database, and offload work to the copies. The main reason for using replication is to scale the use of data in a database without degrading performance on the primary instance.
Read replica
The read replica is an exact copy of the primary instance. Data and other changes on the primary instance are updated in almost real time on the read replica. Send your write transactions to the primary instance, and your read requests to the read replica. The read replica processes queries, read requests, and analytics traffic, thus reducing the load on the primary instance.
Source server
Replication copies transactions from a primary instance to one or more read replicas. The primary instance is also called the source server. The source server can be a Cloud SQL primary instance, or a server outside of Google Cloud, such as an on-premises server or a server running in a different cloud. If the source server is outside of Google Cloud, we call it Replication from an external server.
Cloud SQL Auth proxy client
The Cloud SQL Auth proxy client is open source software maintained by Cloud SQL. It connects to a companion process, the Cloud SQL Auth proxy server, running on your Cloud SQL instance. You run the Cloud SQL Auth proxy client on your own servers. The Cloud SQL Auth proxy client can be used to establish a secure SSL/TLS connection to the database instance, and/or to avoid having to open the firewall. Authentication is done through Identity and Access Management (IAM).

Classification. De-classification and Inspection
Classification is the process to inspect the data and know what data we have, how sensitive it is, and the likelihood. Inspection and classification happen here.
De-identification is the process of removing, masking, replacing information from data.
Reference link- https://cloud.google.com/dlp/docs

Firebase Hosting- Firebase Hosting provides fast and secure hosting for your web app, static and dynamic content, and microservices.
Firebase Hosting is production-grade web content hosting for developers. With a single command, you can quickly deploy web apps and serve both static and dynamic content to a global CDN (content delivery network). You can also pair Firebase Hosting with Cloud Functions or Cloud Run to build and host microservices on Firebase.
Key capabilities of Firebase Hosting:
Serve content over a secure connection:- The modern web is secure. Zero-configuration SSL is built into Firebase Hosting, so content is always delivered securely.
Host static and dynamic content plus microservices:- Firebase Hosting supports all kinds of content for hosting, from your CSS and HTML files to your Express.js microservices or APIs.
Deliver content fast: Each file that you upload is cached on SSDs at CDN edges around the world and served as gzip or Brotli. We auto-select the best compression method for your content. No matter where your users are, the content is delivered fast.