diff --git a/ProjectOrientedSessions/Session04/Session04 Additional Info.md b/ProjectOrientedSessions/Session04/Session04 Additional Info.md
index 651c561..eda4497 100644
--- a/ProjectOrientedSessions/Session04/Session04 Additional Info.md	
+++ b/ProjectOrientedSessions/Session04/Session04 Additional Info.md	
@@ -1,34 +1,24 @@
-### 1. **Should I have an `IEntityService` and then `EntityService` for each of my entities?**
+## *Should I have an `IEntityService` and then `EntityService` for each of my entities?**
 
 Not necessarily **for _every_** entity — only if it **makes sense**.
-
 - The Application Layer should expose **use cases** — not just CRUD logic for each entity.
-    
 - If an entity has business logic or interactions that need orchestration (e.g., validations, aggregations, calling repositories, etc.), then **yes**, create a service.
-    
 - Otherwise, for basic operations, **directly using a repository (via a unit of work or interface)** from the use case handler might be fine.
-### 2. **Is it OK to have services not related to a specific entity?**
+## **Is it OK to have services not related to a specific entity?**
 
 Absolutely, **yes**. In fact, that’s expected in a Clean Architecture setup.
 
 Examples:
-
 - A `ReportGenerationService` that combines bookings, customers, and payments.
-    
 - A `TokenService` for authentication tokens.
-    
 - A `CurrencyConversionService` that hits an external API.
-    
 - A `NotificationService` that sends emails or SMS.
-    
 
 👉 As long as these services **live in the Application Layer** and follow **dependency inversion** (i.e., they depend only on interfaces, not implementations), you’re doing great.
 
-### 3. **Is it necessary to have an interface for each service?**
+## **Is it necessary to have an interface for each service?**
 
-
-
-### 🔹 **What’s the Difference Between Services and Repositories?**
+## **What’s the Difference Between Services and Repositories?**
 
 | Aspect             | **Service**                                                            | **Repository**                                                  |
 | ------------------ | ---------------------------------------------------------------------- | --------------------------------------------------------------- |
@@ -37,7 +27,7 @@ Examples:
 | **Focus**          | Coordinates multiple domain/repo operations, validation, business flow | Fetching/storing data for a specific entity                     |
 | **Example**        | `PlaceOrderService`, `ReportService`                                   | `ICustomerRepository`, `IOrderRepository`                       |
 
-### What does `init` mean?
+## What does `init` mean?
 
 `init` is an **access modifier for properties** that allows you to **set a property only during object initialization**, **but not after**.
 
@@ -62,21 +52,15 @@ Examples:
 ### But when should you prefer `class`?
 
 Use `class` if your DTO or model:
-
 - Needs to be **mutable** after creation
-    
 - Has to **interact with legacy APIs/libraries**
-    
 - Needs **inheritance or polymorphism** (not well supported in `record`)
-    
 - Has **rich behavior** (logic, methods, validation, etc.)
-    
 
 > For example, in the Domain Layer (Entities, ValueObjects), you'll usually stick to **`class`** — because that's where behavior lives.
 
 ## RESTful APIs:
-https://aws.amazon.com/what-is/restful-api/#:~:text=RESTful%20API%20is%20an%20interface,applications%20to%20perform%20various%20tasks.
-
+[read more](https://aws.amazon.com/what-is/restful-api/#:~:text=RESTful%20API%20is%20an%20interface,applications%20to%20perform%20various%20tasks.)
 ## What Conditions Make an API RESTful?
 
 ### Key Principles of REST:
@@ -140,22 +124,15 @@ public class CustomerController : ControllerBase {
 
 
 ## List-like stuff in `C#`
-Absolutely, let’s go over the main “list-like” data types in C#. They all serve similar purposes—holding multiple items—but differ in functionality, performance, and use cases. Here’s a detailed breakdown:
+They all serve similar purposes—holding multiple items—but differ in functionality, performance, and use cases. Here’s a detailed breakdown:
 
 🔷 1. `IEnumerable`
-
 - Namespace: System.Collections.Generic
-    
 - Most basic "list-like" abstraction.
-    
 - Read-only (forward-only iteration).
-    
 - You can use foreach on it.
-    
 - Doesn’t support indexing (no .Count, no [i]).
-    
 - Often used as the return type to expose a stream of data without giving full collection control.
-    
 
 Example:
 
@@ -166,42 +143,28 @@ foreach (var num in numbers)
 ```
 
 💡 Ideal when:
-
 - You want to return a sequence without exposing modification.
-    
 - You’re using LINQ chains.
-    
 - You’re returning data from a database query.
-    
 
 ---
 
 🔷 2. ICollection
-
 - Extends IEnumerable.
-    
 - Adds Count and Add/Remove/Clear methods.
-    
 - Still abstract—List and HashSet implement it.
-    
 
 💡 Useful when:
-
 - You want to expose a collection that can be modified (e.g. Add or Remove).
-    
 - You care about the Count.
     
 
 ---
 
-🔷 3. IList
-
-- Extends ICollection and IEnumerable.
-    
-- Adds index access: list[0] etc.
-    
+🔷 3. `IList`
+- Extends `ICollection` and `IEnumerable`.
+- Adds index access: `list[0]` etc.
 - Think of it like a mutable array with dynamic size.
-    
 
 💡 Use when:
 
@@ -215,15 +178,10 @@ foreach (var num in numbers)
 🔷 4. List
 
 - A concrete class (not interface).
-    
-- Implements IList, ICollection, IEnumerable.
-    
+- Implements `IList`, `ICollection`, `IEnumerable`.
 - Backed by an array (auto-resizes).
-    
 - Fast read and write.
-    
-- Supports Add, Remove, Insert, IndexOf, etc.
-    
+- Supports `Add`, `Remove`, `Insert`, `IndexOf`, etc.
 
 Example:
 
@@ -238,32 +196,23 @@ var second = list[1]; // "Two"
 
 ---
 
-🔷 5. IReadOnlyCollection & IReadOnlyList
+🔷 5. `IReadOnlyCollection` & `IReadOnlyList`
 
-- IReadOnlyCollection: Just Count and IEnumerable.
-    
-- IReadOnlyList: Adds indexing without modification.
-    
+- `IReadOnlyCollection`: Just Count and `IEnumerable`.
+- `IReadOnlyList`: Adds indexing without modification.
 - Used to expose lists safely (read-only).
-    
 
 💡 Used when:
-
 - You want to return a list, but prevent any changes.
-    
 
 ---
 
-🔷 6. Array (T[])
+🔷 6. `Array(T[])`
 
 - Fixed-size.
-    
 - Fastest for indexing.
-    
 - Cannot change size.
-    
-- Implements IList (via Array).
-    
+- Implements `IList` (via Array).
 
 Example:
 
@@ -276,27 +225,20 @@ numbers[0] = 42;
 
 ---
 
-🔷 7. ObservableCollection
+🔷 7. `ObservableCollection`
 
-- For WPF/Blazor/WinForms data-binding.
-    
+- For WPF/`Blazor`/WinForms data-binding.
 - Notifies UI when items are added/removed.
-    
 - Implements IList.
-    
 
 💡 Use in UI apps when the view needs to react to collection changes.
 
 ---
 
 🔷 8. HashSet
-
 - Unordered, no duplicates.
-    
-- Implements ICollection, not IList.
-    
+- Implements `ICollection`, not `IList`.
 - No index access.
-    
 
 💡 Best for fast membership checking (contains x).
 
@@ -315,6 +257,3 @@ numbers[0] = 42;
 |ObservableCollection|✔️|✔️|✔️|✔️|UI binding for collections|
 |HashSet|❌|✔️|❌|❌|Fast lookup, uniqueness enforcement|
 
-—
-
-If you tell me the scenario (e.g. search results, modifying a cart, populating a drop-down), I can recommend the best type for it. Want that?
diff --git a/ProjectOrientedSessions/Session04/Session04 Backend.md b/ProjectOrientedSessions/Session04/Session04 Backend.md
index f5e5bcb..bb9021f 100644
--- a/ProjectOrientedSessions/Session04/Session04 Backend.md	
+++ b/ProjectOrientedSessions/Session04/Session04 Backend.md	
@@ -1,19 +1,20 @@
-# Preparation: 
+
+
+# 🛠️ Task Checklist
+
+## Preparation: 
 The unedited conversation with Chat GPT, concerning almost all of the aspects of this session:
 (optional): read this to get a better understanding of the topic:
 https://chatgpt.com/share/67f18460-1c1c-8010-bc57-9f3b683ec87a
 
-# Branching
+## 🚧Branching
 - [ ]  Create the feature/transportation-search branch based on develop
 
-# DTO
+## DTO
 In order to develop transportation search flow, three DTOs need to be created in the application layer.
 
 - [ ]  Create DTOs related to transportation search flow
-
 📂 Suggested Folder: Application/DTOs/City`
-
-
 ```cs
 public class CityDto
 {
@@ -23,34 +24,35 @@ public class CityDto
 ```
 
 📂 Suggested Folder: Application/DTOs/Transportation
-
 ```cs
 public class TransportationSearchRequestDto
 {
      public short? VehicleTypeId { get; init; }
-     public int? FromCityId { get; init; }
-     public int? ToCityId { get; init; }
-     public DateTime? StartDate { get; init; }
-     public DateTime? EndDate { get; init; }
-}
+public int? FromCityId { get; init; }
+public int? ToCityId { get; init; }
+public DateTime? StartDate { get; init; }
+public DateTime? EndDate { get; init; }
 ```
 
 ```cs
 public class TransportationSearchResultDto
 {
     public long Id { get; init; }
-    public required string CompanyTitle { get; init; }   
-    public required string FromLocationTitle { get; init; }
-    public required string ToLocationTitle { get; init; }
-    public required string FromCityTitle { get; init; }
-    public required string ToCityTitle { get; init; }
-    public DateTime StartDateTime { get; init; }
-    public DateTime? EndDateTime { get; init; }
-    public decimal Price { get; init; } 
-}
+public int VehicleTypeId { get; init; }   
+public string? VehicleTitle { get; init; }   
+public required string CompanyTitle { get; init; }   
+public required string FromLocationTitle { get; init; }
+public required string ToLocationTitle { get; init; }
+public required string FromCityTitle { get; init; }
+public required string ToCityTitle { get; init; }
+public DateTime StartDateTime { get; init; }
+public DateTime? EndDateTime { get; init; }
+public decimal Price { get; init; }
+public int RemainingCapacity { get; init; }
+
 ```
 
-# Repository
+## Repository
 There are a few things to be add to some repositories for transportation search flow.
 
 - [ ] Create DTOs related to transportation search flow
@@ -108,7 +110,7 @@ public class TransportationRepository :
 ```
 
 
-# Auto Mapper
+## Auto Mapper
 Auto Mapper simplifies mapping between aggregates and DTOs in both directions.
 
 - [ ] Create a `MappingProfile` that inherits `Profile`, and use it to add configurations for mappings
@@ -157,7 +159,7 @@ public class MappingProfile : Profile
  .
 ```
 
-# Result & Result Status
+## Result & Result Status
 
 - [ ] Create `ResultStatus` enum and `Result` class
 📂 Suggested Folder: Application/Result
@@ -220,22 +222,18 @@ public enum ResultStatus
 You can read more about enums: [W3Schools](https://www.w3schools.com/cs/cs_enums.php)
 
 
-# `IService` & Service
+## `IService` & Service
 
 Now, use `I[Entity]Repositry` and `IUnitOfWork` in services to implement business logic
-
 - [ ] Create `I[Entity]Service` and `[Entity]Service` which implements it
 
 📂 Suggested Folder for `I[Entity]Service`: Application/Interfaces
 
 📂 Suggested Folder for Services: Application/Services
-
-
 - existence of an interface for each service class is optional
 - services can have multiple repositories in them -> logic-based structure
 
 An example of `I[Entity]Service`:
-
 ```c#
 public interface ITransportationService
 {
@@ -244,7 +242,6 @@ public interface ITransportationService
 ```
 
 An example of `[Entity]Service`:
-
 ```cs
 public class TransportationService : ITransportationService
 {
@@ -291,7 +288,7 @@ builder.Services.AddScoped<ICityService, CityService>();
 .
 ```
 
-# Controller
+## Controller
 Now we're getting to endpoints, you should communicate with client side through web-api. So every controller uses Services in Application layer to receive requests and send responses with DTOs.
 
 - [ ] Create an APIController (right click on the folder, and then under Add, select Controller, and then make sure to select the APIController type)
@@ -336,17 +333,16 @@ public class TransportationController : ControllerBase
 }
 ```
 
-- HttpGet: handles a GET request from client -> important for routing
-- Ok, BadRequest, NotFound and StatusCode are Json results to send through api
-- Use TransportationService to communicate with Application
+- `HttpGet`: handles a GET request from client -> important for routing
+- Ok, `BadRequest`, `NotFound` and `StatusCode` are json results to send through API
+- Use `TransportationService` to communicate with Application
 
-# Inserting Sample Data 
+## Inserting Sample Data 
 
 For testing purposes, add some data into the related tables. 
 You are provided with a SQL script, that adds some sample data into the following tables
 
  **Important Notes:** Note that different database names, and different table names will produce errors while executing the script. Consider adjusting these names before executing the script
- 
 - Cities 
 - Companies 
 - LocationTypes
@@ -356,8 +352,14 @@ You are provided with a SQL script, that adds some sample data into the followin
 - Transportation
 
 - [ ] Open `TransportationRelatedSampleData.sql` with SSMS, and execute the query
+> Note: there has been changes in database structure since this note and this file has been written. 
 
 
-# Merge
+## 🚧Merge
 - [ ] Create a PR and merge the current branch with develop
 
+# 🧠 Hints & Notes
+# 🙌 Acknowledgements
+
+- ChatGPT for snippet refinement and explanations
+# 🔍 References