Vertical scaling involves adding more resources to a single server, while horizontal scaling involves distributing the load across multiple servers. Load balancing and sharding are techniques used to distribute the load across multiple servers.

Performance optimization in SaaS applications aims to achieve all of the above objectives: reducing latency, improving throughput, and minimizing resource usage.

Regularly backing up data is important for data protection, but it is not a best practice for ensuring high availability. High availability is achieved through techniques such as using redundant servers, implementing load balancing, and avoiding single points of failure.

Sharding involves dividing a large dataset into smaller, more manageable chunks and distributing them across multiple servers. This helps improve query performance, reduce latency, and increase scalability.

Uptime is a measure of the availability of a system, while latency, throughput, and resource utilization are performance metrics that measure the speed, capacity, and efficiency of a system.

A CDN is a network of servers distributed across different locations that store and deliver content to users based on their geographic proximity. This helps reduce latency by delivering content from a server that is closer to the user.

Optimizing performance is not a scalability challenge, but rather a goal that is pursued to ensure that the application can handle increasing loads and maintain a high level of performance.

Load balancing is used to distribute incoming traffic across multiple servers, thereby improving scalability and preventing any single server from becoming overloaded.

Load balancing is a technique used to improve scalability, not reliability. Implementing redundancy, regularly testing and monitoring, and avoiding single points of failure are all best practices for ensuring reliability.

Caching involves storing frequently accessed data in memory to reduce the time required to retrieve it. This helps improve query performance, reduce latency, and improve overall application responsiveness.

Denormalization is a technique used to improve query performance by duplicating data across multiple tables, while horizontal scaling, vertical scaling, and load balancing are techniques used to improve scalability.

A microservices architecture involves breaking down an application into smaller, independent services, which can be scaled, deployed, and maintained independently. This improves scalability, modularity, and ease of deployment.

Increasing the number of servers is a scalability technique, not a performance optimization technique. Performance optimization techniques aim to improve the efficiency of the application without adding more resources.

A circuit breaker is a mechanism that monitors the health of a service and temporarily disables it if it becomes unavailable or unresponsive. This helps prevent cascading failures, improve fault tolerance, and reduce latency by avoiding unnecessary retries.

Overprovisioning resources is not a best practice for scalability, as it can lead to wasted resources and increased costs. Scalability should be achieved through techniques such as using a microservices architecture, implementing horizontal scaling, and avoiding single points of failure.