Async / Await and Task-Based Programming

C# in Visual Studio 2026 — a hands-on guide for developers at every level.

Why Async?

I/O operations (network requests, file reads, database queries) can take hundreds of milliseconds. async/await lets your thread do other work while waiting, keeping applications responsive without the complexity of manual threading.

async and await

using System.Net.Http;

static async Task<string> FetchAsync(string url)
{
    using var client = new HttpClient();
    string content = await client.GetStringAsync(url);
    return content[..Math.Min(100, content.Length)]; // first 100 chars
}

string html = await FetchAsync("https://example.com");
Console.WriteLine(html);

Task and Task<T>

Parallel Tasks

static async Task RunParallelAsync()
{
    Task<int> t1 = Task.Run(() => HeavyWork(1));
    Task<int> t2 = Task.Run(() => HeavyWork(2));

    int[] results = await Task.WhenAll(t1, t2);
    Console.WriteLine($"Results: {results[0]}, {results[1]}");
}