Learn Security & performance.
Protect application boundaries and investigate production failures.
Security & performance essentials
Start with the essentials or pick the concept you need.
01PerformanceExplore concepts
02SecurityExplore concepts
- Authentication vs authorization vs RBAC?2 min
- What makes JWT or session authentication safe?2 min
- How should I store passwords and secrets?2 min
- XSS vs CSRF vs CORS?2 min
- How do I prevent SQL injection, NoSQL injection and SSRF?2 min
- What are least privilege, TLS and secure headers?2 min
- Is rate limiting enough to prevent every attack?2 min
03ObservabilityExplore concepts
What you will study in Security & performance
Focused lessons organized by concept. Start with the explanation, trace the examples, and check your recall before moving on.
Performance
Big-O describes how an algorithm's work or memory grows as the input grows. Profiling measures where a particular application spends time or retains memory during a real workload. They complement each other: growth rate explains future scaling, while profiling locates the current bottleneck.
Security
Authentication checks the caller's identity, authorization decides whether that identity may perform an action, and RBAC groups permissions into roles. These checks work together but answer different questions. A logged-in employee should not automatically gain access to every employee's records.
- Authentication vs authorization vs RBAC?
- What makes JWT or session authentication safe?
- How should I store passwords and secrets?
- XSS vs CSRF vs CORS?
- How do I prevent SQL injection, NoSQL injection and SSRF?
- What are least privilege, TLS and secure headers?
- Is rate limiting enough to prevent every attack?
Observability
Observability means understanding a system's behavior from the information it emits. Logs capture events, metrics summarize measurements over time, and traces connect work across a request path. An SLI is a measured service behavior, while an SLO is the target the team aims to meet over a defined period.