What is Serialization and Deserialization?

Serialization and Deserialization are very common interview questions in .NET.

🔹 What is Serialization?

Serialization is the process of converting an object into a format that can be:

Stored in file
Sent over network
Saved in database
Cached

Usually converted into:

JSON
XML
Binary

Example

public class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
}

Serialization converts this object:

Employee emp = new Employee { Id = 1, Name = "Sampath" };

Into JSON:

{
  "Id": 1,
  "Name": "Sampath"
}

🔹 What is Deserialization?

Deserialization is the reverse process.

It converts:

👉 JSON / XML → Object

Example:

{
  "Id": 1,
  "Name": "Sampath"
}

Converted back into:

Employee emp = new Employee();

🔹 Real World Example

When you call an API:

API Response (JSON)

{
  "id": 10,
  "title": "Article Title"
}

Your application converts it to:

Article article = response;

👉 This is Deserialization

🔹 Serialization Example in .NET

Using System.Text.Json

using System.Text.Json;

Employee emp = new Employee { Id = 1, Name = "Sampath" };

string json = JsonSerializer.Serialize(emp);

Console.WriteLine(json);

🔹 Deserialization Example

string json = "{\"Id\":1,\"Name\":\"Sampath\"}";

Employee emp = JsonSerializer.Deserialize<Employee>(json);

🔹 Another Popular Library

Many developers also use
Newtonsoft.Json

Example:

using Newtonsoft.Json;

string json = JsonConvert.SerializeObject(emp);

Employee emp = JsonConvert.DeserializeObject<Employee>(json);

🔹 Why Do We Use Serialization?

We use serialization for:

Web APIs
Microservices communication
Saving data to files
Caching (Redis)
Session storage

🔹 Interview One-Line Answer

Serialization → Convert Object → JSON/XML
Deserialization → Convert JSON/XML → Object

🔹 Interview Follow-Up Questions

Which is faster?

✅ System.Text.Json (faster, built-in)

Which is more flexible?

✅ Newtonsoft.Json (more features)

🔹 Very Common Interview Example

ASP.NET Core Controller:

[HttpPost]
public IActionResult Save(Employee emp)
{
    return Ok(emp);
}

Here:

Request JSON → Deserialization
Response Object → Serialization