هل من الممكن شرح مفصل ل OOP

السلام عليكم

هل من الممكن شرح البرمجة الكائنات OOP بلغة C# فى ASP.NET حيث انى قمت بالبحث ولم اجد موضوع خاص لشرح برمجة الكائنات

وهل هذا الكود برمجة كائنات

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

/// <summary>
/// Summary description for Category
/// </summary>
public class Category
{
    private long iD;

    public long ID
    {
        get { return iD; }
        set { iD = value; }
    }
    private String categoryName;

    public String CategoryName
    {
        get { return categoryName; }
        set { categoryName = value; }
    }
    private String categoryPicture;

    public String CategoryPicture
    {
        get { return categoryPicture; }
        set { categoryPicture = value; }
    }


	public Category()
	{


		//
		// TODO: Add constructor logic here
		//
	}
}

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;
using System.Collections.ObjectModel;


/// <summary>
/// Summary description for CategoriesDAL
/// </summary>
public class CategoriesDAL
{
    SqlConnection conn;
    SqlCommand command;
    SqlDataReader reader;

	public CategoriesDAL()
	{
        conn = new SqlConnection();
        conn.ConnectionString = ConfigurationManager.ConnectionStrings["ProductConnectionString"].ToString();
        command = new SqlCommand();
        command.Connection = conn;
	}

    private Category GetObjectFromReader(SqlDataReader data)
    {
        Category obj = new Category();

        obj.ID = (long)data["id"];
        obj.CategoryName = (String)data["CategoryName"];
        obj.CategoryPicture = @"CategoryPictures/" + obj.ID.ToString() + (String)data["CategoryPicture"];

        return obj;
    }

    private void FillCollectionFromReader(SqlDataReader data, Collection<Category> list)
    {
        while (data.Read())
        {
            Category obj = GetObjectFromReader(data);
            list.Add(obj);
        }
    }

    public Collection<Category> GetAllCategories()
    {
        command.CommandText = "GetCategories";
        command.CommandType = CommandType.StoredProcedure;
        conn.Open();
        reader = command.ExecuteReader();
        Collection<Category> cate_List = new Collection<Category>();
        FillCollectionFromReader(reader, cate_List);

        conn.Close();
        return cate_List;

    }

    public void AddCategory(Category cate)
    {
        command.Parameters.Clear();
        command.CommandText = "AddCategory";
        command.CommandType = CommandType.StoredProcedure;

        command.Parameters.Add("@categoryName", cate.CategoryName);
        command.Parameters.Add("@categoryPicture", cate.CategoryPicture);

        conn.Open();
        command.ExecuteNonQuery();

        conn.Close();

    }
}

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