.NET / C#
.NET is Microsoft’s open-source platform for building web, desktop, mobile and cloud applications; C# is the primary language in the .NET ecosystem.
.NET and C# form one of the most powerful ecosystems for professional software development. Since the open-source shift in 2016, .NET has evolved from a Windows-only platform to a cross-platform framework running on Windows, Linux and macOS. C# consistently ranks in the TIOBE top 5 and is used by millions of developers worldwide – from startups to Fortune 500.
What is .NET / C#?
.NET (formerly .NET Core, unified since version 5) is an open-source platform from Microsoft for building many application types: web APIs (ASP.NET Core), web apps (Blazor), desktop (WPF, WinForms, MAUI), mobile (.NET MAUI), microservices, cloud functions and games (Unity). C# is a modern, type-safe, object-oriented language with LINQ, async/await, pattern matching, records and nullable reference types. The CLR runs compiled IL code and provides garbage collection, JIT or AOT compilation. NuGet is the package manager with 350,000+ packages.
How does .NET / C# work?
C# code is compiled by the Roslyn compiler to Intermediate Language (IL), which the .NET runtime executes. The JIT compiler compiles IL to native code at runtime – optimized for the CPU. Alternatively AOT compiles directly to native for faster startup (ideal for serverless and mobile). NuGet manages dependencies. The .NET CLI handles create, build, test and deploy. Dependency injection is first-class in ASP.NET Core; Kestrel is one of the fastest HTTP servers.
Practical Examples
Stack Overflow: One of the world’s most visited sites runs on ASP.NET and C# – proof of platform performance and scalability.
An insurance group builds core insurance software with .NET: millions of policies, complex rating and regulatory requirements – C# provides the type safety.
A game studio uses Unity with C# for a mobile game on iOS and Android – over 70% of mobile games are made with Unity.
A logistics company builds microservices with ASP.NET Core Minimal APIs in Docker on Kubernetes – sub-5 ms response times.
A startup builds a cross-platform app with .NET MAUI: one codebase for iOS, Android, Windows and macOS with native performance and UI.
Typical Use Cases
Enterprise web: ASP.NET Core for high-performance, secure web APIs and web applications
Microservices: Lightweight containerized services with Minimal APIs and gRPC
Desktop: WPF, WinForms or .NET MAUI for Windows and cross-platform desktop apps
Cloud-native: Azure Functions, AWS Lambda and containerized services on Kubernetes
Game development: Unity with C# as the leading platform for mobile and indie games
Advantages and Disadvantages
Advantages
- Performance: .NET is among the fastest frameworks – regularly in TechEmpower top 3
- Type safety: C# and nullable reference types prevent many error classes at compile time
- Cross-platform: .NET runs on Windows, Linux and macOS – Docker and cloud deployment are straightforward
- Complete ecosystem: Web, desktop, mobile and cloud from one platform and one language
- Enterprise-ready: Long-term Microsoft support, proven patterns and a huge library ecosystem
Disadvantages
- Historical Windows focus: Despite cross-platform, some libraries and tools are still Windows-centric
- Learning curve: C# is a rich language – LINQ, async/await, generics and pattern matching need time
- Fragmentation: .NET Framework (legacy) vs. .NET 8+ can confuse when migrating
- Less common in startup ecosystem: Compared to Node.js or Python the .NET startup community is smaller
Frequently Asked Questions about .NET / C#
What is the difference between .NET Framework and .NET 8?
Is C# hard to learn?
Is .NET suitable for startups?
Related Terms
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