System design terms 

Application Programming Interface (API)

• Definition: API is a set of rules and protocols that allow different software applications to communicate with each other. It enables requests from one system (e.g., a frontend application, mobile app, or third-party service) to retrieve or send data to another system (e.g., a backend server, database, or external service). This effortless data exchange affects overall system functionality and scalability.

• Why important for PMs: APIs let different apps and services talk to each other, making products more powerful and connected. PMs need to understand how they work to define features, scale efficiently, and support partnerships without getting stuck in technical roadblocks. 

• Example Sentence: "Last week we integrated a third-party API for real-time payments, reducing development time and improving the user experience."

• Related Terms: REST API, Swagger, Webhooks

Availability

• Definition: System Design Term. The degree to which a system remains operational and accessible.

• Why important for PMs: PMs must ensure high availability to minimize downtime and maintain a seamless user experience.

• Example Sentence: "Our system's availability target is 99.99% uptime to support mission-critical operations."

• Related Terms: High Availability (HA), Fault Tolerance, Failover Mechanism

Caching

• Definition: Storing frequently used data temporarily in a fast-access location to speed up performance.

• Why important for PMs: Caching makes apps faster by reducing the need to repeatedly fetch data from a slow database. PMs should understand caching to improve user experience and reduce infrastructure costs.

• Example Sentence: "We should cache frequently accessed data to reduce database queries and improve load times."

• Related Terms: Database, Latency, CDN

CAP Theorem 

• Definition: System Design Term. A principle that states a distributed system can only guarantee two out of three: Consistency, Availability, and Partition Tolerance.

• Why important for PMs: PMs working on distributed applications must understand trade-offs between these three factors.

• Example Sentence: "When designing our database architecture, we had to decide between prioritising consistency and availability under the constraints of CAP Theorem."

• Related Terms: Consistency Models, Distributed Systems, Partition Tolerance

CDN (Content Delivery Network)

• Definition: A network of servers distributed worldwide that helps deliver images, videos, and other content quickly by serving them from the nearest location.

• Why important for PMs: CDNs make websites load faster for users everywhere and reduce server load. PMs working on global products should know how CDNs improve speed and reliability.

• Example Sentence: "Since our users are global, let's use a CDN to speed up content delivery and reduce latency."

• Related Terms: Caching, Latency, Load Balancer

Continuous Integration/Continuous Deployment (CI/CD)

• Definition: CI/CD is a software development practice that automates the process of integrating code changes, testing, and deploying them to production. Continuous Integration (CI) ensures that developers frequently merge code into a shared repository, where automated tests validate changes. Continuous Deployment (CD) then automates the release process, enabling rapid and reliable delivery of new features and bug fixes with minimal manual intervention.

• Why important for PMs:  Understanding CI/CD is crucial for Product Managers because it directly impacts release velocity, product quality, and team efficiency.  Having CI/Cd set up can ensure faster feature delivery, reduce deployment risks, and maintain a smooth user experience while aligning development processes with business goals. 

• Example Sentence: "By implementing CI/CD, our team reduced the time it takes to release new features from weeks to days."

• Related Terms: DevOps, Version Control, Automated Testing

Data Pipeline

• Definition: The automated process of collecting, moving, and transforming data from one place to another for analysis or use.

• Why important for PMs: Data pipelines help power analytics, machine learning, and personalized user experiences. PMs need to know how data flows to make informed product decisions.

• Example Sentence: "We need a reliable data pipeline to ensure real-time analytics for our dashboard.

• Related Terms: ETL (Extract, Transform, Load), Observability

Diagonal Scaling (Hybrid Scaling)

• • Definition: A combination of vertical and horizontal scaling, where a system is scaled up (more power to a single machine) until it reaches its limit, then scaled out (adding more machines).

  • Why important for PMs: Diagonal scaling provides flexibility, helping products grow efficiently without immediate infrastructure overhauls. PMs should plan when to switch from vertical to horizontal scaling.

  • Example Sentence: "Instead of immediately switching to horizontal scaling, let's use diagonal scaling—first upgrade our servers, then add more machines when needed."

  • Related Terms: Horizontal Scaling, Vertical Scaling, Scalability

Fault Tolerance

• Definition: The ability of a system to keep running even when some parts fail.

• Why important for PMs: Users expect products to always work. PMs should understand fault tolerance to ensure reliability and minimise downtime.

• Example Sentence: "Next sprint we aim to make our system fault-tolerant so a single server failure won’t cause downtime."

• Related Terms: High Availability, Redundancy, Load Balancer

Horizontal Scaling

• Definition: Adding more machines or servers to handle increased load, instead of upgrading a single machine (vertical scaling).

• Why important for PMs: Horizontal scaling helps products grow efficiently without performance bottlenecks. PMs should understand when to scale horizontally to ensure smooth user experiences.

• Example Sentence: "As traffic grows, we should plan for horizontal scaling by adding more servers instead of overloading a single one."

• Related Terms: Scalability, Load Balancer, Fault Tolerance

Latency

• • Definition: The time delay between a user request and a system response, measured in milliseconds.

  • Why important for PMs: Lower latency means a faster product experience. PMs should optimize latency to improve responsiveness, especially for real-time apps.

  • Example Sentence: "Our checkout page is slow—let’s analyze latency issues and optimize API response times."

  • Related Terms: API, Caching, CDN

Lazy Loading

• Definition: A technique that delays loading non-essential content (such as images or videos) until it’s needed, improving initial load time and performance.

• Why important for PMs: Lazy loading enhances user experience, reduces bandwidth consumption, and improves page speed, which is crucial for SEO and engagement.

• Example Sentence: "We implemented lazy loading for images, reducing our homepage load time by 40%."

• Related Terms: Load Time, Performance Optimization, Infinite Scroll

Load Balancer

• Definition: A tool that distributes incoming traffic across multiple servers to prevent overload and crashes.

• Why important for PMs: Load balancers keep products running smoothly under heavy traffic. PMs need to plan for scalability and reliability.

• Example Sentence: "Traffic is spiking during peak hours; we need a load balancer to distribute requests evenly." 

Related Terms: Scalability, Fault Tolerance

Load Time

• Definition: The time it takes for a webpage or application to fully display its content. Faster load times improve user experience and retention.

• Why important for PMs: Slow load times lead to higher bounce rates and lower engagement. PMs must prioritise performance optimisations like caching, image compression, and lazy loading.

• Example Sentence: "We reduced our load time from 5 seconds to 2 seconds, improving user retention by 20%."

• Related Terms: Performance Optimisation, Core Web Vitals, Lazy Loading

Microservices

• Definition: An architecture where an application is broken into small, independent services that work together.

• Why important for PMs: Microservices allow products to scale and evolve faster. PMs need to understand their benefits and trade-offs, like easier updates but higher complexity.

• Example Sentence: "Breaking this feature into microservices will allow us to update it independently without affecting the whole system."

• Related Terms: Monolithic Architecture, Scalability, API

Monolithic Architecture

• Definition: A traditional software design where the entire application is built as a single, interconnected unit.

• Why important for PMs: Monolithic apps are simpler to start but harder to scale. PMs need to decide when to use monolithic vs. microservices architectures.

• Example Sentence: "Our monolithic architecture is making deployments risky; should we consider migrating to microservices?"

• Related Terms: Microservices, Scalability

Observability (Logs, Metrics, Tracing)

• Definition: The ability to monitor and understand a system’s health and behaviour using logs, metrics, and tracing data.

• Why important for PMs: Observability helps teams quickly detect and fix issues, ensuring a smooth user experience. PMs should advocate for good monitoring to minimise downtime.

• Example Sentence: "We need better observability—let’s add more logging and monitoring to track system issues proactively."

• Related Terms: Fault Tolerance, Data Pipeline

Rate Limiting

• Definition: A control mechanism that limits the number of requests a user or system can make in a given time.

• Why important for PMs: Rate limiting prevents system overload and abuse (e.g., bots spamming an API). PMs should know how it impacts user experience and security.

• Example Sentence: "We should add rate limiting to our API to prevent abuse and ensure fair usage."

• Related Terms: API, Scalability, Load Balancer

Redundancy

• Definition: Duplicating system components (e.g., servers, databases) to prevent failure and improve reliability.

• Why important for PMs: Redundancy minimises downtime by ensuring there’s a backup if something fails. PMs should balance redundancy with cost and complexity.

• Example Sentence: "To improve uptime, we need redundancy in our database architecture, so no single failure takes the system down."

• Related Terms: Fault Tolerance, Replication, High Availability

Replication

• Definition: Copying data across multiple servers or databases to improve availability, reliability, and performance.

• Why important for PMs: Replication ensures users get fast, reliable access to data, even during failures. PMs should consider replication for high-traffic or global products.

• Example Sentence: "We should enable database replication across regions to reduce latency and improve disaster recovery."

• Related Terms: Redundancy, Fault Tolerance, Scalability

Scalability

• Definition: The ability of a system to handle growth, whether more users, data, or traffic.

• Why important for PMs: Scalable products can support more users without slowing down. PMs must plan for scalability to ensure long-term success.

• Example Sentence: "Can our system scale to handle 10x more users, or do we need architectural changes?"

• Related Terms: Load Balancer, Microservices, Serverless Computing

Serverless Computing

• • Definition: Running code without managing servers, where cloud providers handle the infrastructure (e.g., AWS Lambda).

  • Why important for PMs: Serverless reduces costs and allows products to scale automatically. PMs should consider it for event-driven or infrequent workloads.

  • Example Sentence: "For this event-driven feature, let’s consider serverless computing to optimise costs and scalability."

  • Related Terms: Scalability, Fault Tolerance

Stateful vs. Stateless Systems

• Definition: A stateful system remembers past interactions and stores data about them, while a stateless system treats each request as independent, without storing session data.

• Why important for PMs: Understanding this helps PMs make informed decisions about performance, scalability, and user experience—stateful systems enable personalised interactions, while stateless systems scale more easily.

• Example Sentence: "Since our API needs to handle high traffic efficiently, we should design it to be stateless instead of relying on stored sessions."

• Related Terms: API, Scalability, Fault Tolerance

Version Control

• • Definition: A system (e.g., Git) that tracks changes to code, allowing teams to collaborate, roll back errors, and manage software updates.

  • Why important for PMs: Version control helps ensure smooth development workflows and reduces risks when shipping new features. PMs should understand its role in product releases and engineering velocity.

  • Example Sentence: "Before we release the update, let’s check the version control history to see recent changes and potential conflicts."

  • Related Terms: CI/CD (Continuous Integration/Continuous Deployment), Rollback, Git

Vertical Scaling (Scaling Up)

• Definition: Increasing the capacity of a single machine by adding more CPU, RAM, or storage instead of adding multiple machines.

• Why important for PMs: Vertical scaling is a quick way to handle more traffic, but it has hardware limits and can be costly. PMs should consider when to scale vertically vs. shifting to horizontal scaling.

• Example Sentence: "Our database is slowing down—before adding more servers, let's see if vertical scaling (upgrading CPU and RAM) is a better option."

• Related Terms: Horizontal Scaling, Scalability, Load Balancer