diff --git a/Colaborators/colaborators.md b/Colaborators/colaborators.md
index ddb715d..a85f034 100644
--- a/Colaborators/colaborators.md
+++ b/Colaborators/colaborators.md
@@ -1,39 +1,35 @@
+
 # Our Amazing Collaborators 🌟
 
 Thank you to all the wonderful people who have contributed to this project!
 
----
-
 1. Harry Guajan
 [@Harry-GNS](https://github.com/Harry-GNS)
 Ecuador 🇪🇨
 "To see the world, things dangerous to come to, to see behind walls, draw closer, to find each other and to feel. That is the purpose of life."
 
----
-
 2. Srijani Das  
 [@Srijani-Das07](https://github.com/Srijani-Das07)  
 India 🇮🇳 
 "Small steps, lasting impact."
 
----
-
 3. Ofek Hodis
 [@Ofek-Hodis](https://github.com/Ofek-Hodis)
 Anonymous :)
 "It is necessary to have been ruined over generations repairing the old, crumbling castle in order to learn to love it."
 
----
-
 4. Shanmukh
 [@krishn212](https://github.com/krishn212)
 India 🇮🇳
 "The secret of getting ahead is getting started."
 
----
-
 1. Shyamsundar  
 [@Shyamsundar-eng](https://github.com/Shyamsundar-eng)  
 India 🇮🇳  
 "Learning in public, one commit at a time."
 
+2. Diego Alexander  
+[@Dm2998](https://github.com/Dm2998)  
+Ireland 🇮🇪  
+"Every small commit is a step toward becoming a better developer."
+
diff --git a/new_projects/banking_system/accounts.py b/new_projects/banking_system/accounts.py
index d7aed7e..9d16c5e 100644
--- a/new_projects/banking_system/accounts.py
+++ b/new_projects/banking_system/accounts.py
@@ -1,43 +1,48 @@
+class InsufficientFundsError(Exception):
+    """Raised when withdrawal amount exceeds available balance."""
+    pass
+
+
 class Account:
-    def __init__(self, account_number, customer_name, initial_balance=0):
-        self.__account_number = account_number
-        self.__customer_name = customer_name
-        self.__balance = initial_balance
+    """Represents a bank account."""
+
+    def __init__(self, account_number: str, customer_name: str, initial_balance: float = 0.0):
+        self._account_number = account_number
+        self._customer_name = customer_name
+        self._balance = initial_balance
 
     @property
     def account_number(self):
-        return self.__account_number
+        return self._account_number
 
     @property
     def customer_name(self):
-        return self.__customer_name
+        return self._customer_name
 
     @property
     def balance(self):
-        return self.__balance
+        return self._balance
 
-    def deposit(self, amount):
+    def deposit(self, amount: float) -> float:
+        """Deposit a positive amount into the account."""
         if amount <= 0:
             raise ValueError("Deposit amount must be positive.")
-        self.__balance += amount
-        return self.__balance
-    
-    def to_dict(self):
-        return {
-            "account_number": self.__account_number,
-            "customer_name": self.__customer_name,
-            "balance": self.__balance
-        }
+        self._balance += amount
+        return self._balance
 
-    def withdraw(self, amount):
+    def withdraw(self, amount: float) -> float:
+        """Withdraw a positive amount from the account."""
         if amount <= 0:
             raise ValueError("Withdrawal amount must be positive.")
-        if self.__balance >= amount:
-            self.__balance -= amount
-            return self.__balance
-        else:
+        if amount > self._balance:
             raise InsufficientFundsError("Insufficient funds.")
+        self._balance -= amount
+        return self._balance
 
-class InsufficientFundsError(Exception):
-    pass
-
+    def to_dict(self) -> dict:
+        """Convert account data to dictionary for persistence."""
+        return {
+            "account_number": self._account_number,
+            "customer_name": self._customer_name,
+            "balance": self._balance
+        }
diff --git a/new_projects/banking_system/bankmanager.py b/new_projects/banking_system/bankmanager.py
index a71622f..ae64eee 100644
--- a/new_projects/banking_system/bankmanager.py
+++ b/new_projects/banking_system/bankmanager.py
@@ -1,62 +1,78 @@
+import json
+import os
+import random
 from accounts import Account
-import random,os,json
+
+
+class AccountIDError(Exception):
+    """Raised when an account ID is invalid or already exists."""
+    pass
+
+
+BASE_DIR = os.path.dirname(os.path.abspath(__file__))
+DATA_FILE = os.path.join(BASE_DIR, "accounts.json")
 
 
 class BankManager:
+    """Handles account creation, transactions, and persistence."""
+
     def __init__(self):
-        self.__accounts = {}
+        self._accounts = {}
         self.load_accounts()
 
     def load_accounts(self):
-        if os.path.exists("accounts.json"):
-            with open("accounts.json", "r") as f:
-                accounts_data = json.load(f)
-                for acc_id, acc_info in accounts_data.items():
-                    account = Account(acc_info["account_number"], acc_info["customer_name"], acc_info["balance"])
-                    self.__accounts[acc_id] = account
+        """Load accounts from JSON file if it exists."""
+        if os.path.exists(DATA_FILE):
+            with open(DATA_FILE, "r") as file:
+                data = json.load(file)
+                for acc_id, info in data.items():
+                    self._accounts[acc_id] = Account(
+                        info["account_number"],
+                        info["customer_name"],
+                        info["balance"]
+                    )
 
     def save_accounts(self):
-        accounts_data = {acc_id: acc.to_dict() for acc_id, acc in self.__accounts.items()}
-        with open("accounts.json", "w") as f:
-            json.dump(accounts_data, f, indent=4)   
+        """Save all accounts to JSON file."""
+        with open(DATA_FILE, "w") as file:
+            json.dump(
+                {acc_id: acc.to_dict() for acc_id, acc in self._accounts.items()},
+                file,
+                indent=4
+            )
 
-    def create_account_id(self):
+    def create_account_id(self) -> str:
+        """Generate a unique account ID."""
         while True:
-            account_id = str(random.randint(100000, 999999))
-            if account_id not in self.__accounts:
-                return account_id
-
-    def create_account(self, account_id, name, initial_deposit=0.0):
-        if account_id in self.__accounts:
-            raise iderror("Account ID already exists.")
-        new_account = Account(account_id, name, initial_deposit)
-        self.__accounts[account_id] = new_account
+            acc_id = str(random.randint(100000, 999999))
+            if acc_id not in self._accounts:
+                return acc_id
+
+    def create_account(self, name: str, initial_deposit: float) -> Account:
+        """Create a new bank account."""
+        acc_id = self.create_account_id()
+        account = Account(acc_id, name, initial_deposit)
+        self._accounts[acc_id] = account
         self.save_accounts()
-        return new_account
-    
-    def get_account(self, account_id):
-        return self.__accounts.get(account_id, None)
-
-    def deposit_to_account(self, account_id, amount):
-        account = self.get_account(account_id)
-        if account:
-            self.save_accounts()
-            return account.deposit(amount)
-        else:
-            raise iderror("Account ID does not exist.")
-
-    def withdraw_from_account(self, account_id, amount):
-        account = self.get_account(account_id)
-        if account:
-            self.save_accounts()
-            return account.withdraw(amount)
-        raise iderror("Account ID does not exist.")
-
-    def get_account_balance(self, account_id):
-        account = self.get_account(account_id)
-        if account:
-            return account.balance
-        return None
-    
-class iderror(Exception):
-    pass
\ No newline at end of file
+        return account
+
+    def get_account(self, acc_id: str) -> Account:
+        account = self._accounts.get(acc_id)
+        if not account:
+            raise AccountIDError("Account ID does not exist.")
+        return account
+
+    def deposit(self, acc_id: str, amount: float) -> float:
+        account = self.get_account(acc_id)
+        account.deposit(amount)
+        self.save_accounts()
+        return account.balance
+
+    def withdraw(self, acc_id: str, amount: float) -> float:
+        account = self.get_account(acc_id)
+        account.withdraw(amount)
+        self.save_accounts()
+        return account.balance
+
+    def get_balance(self, acc_id: str) -> float:
+        return self.get_account(acc_id).balance
diff --git a/new_projects/banking_system/main.py b/new_projects/banking_system/main.py
index f1c1a47..23a04c1 100644
--- a/new_projects/banking_system/main.py
+++ b/new_projects/banking_system/main.py
@@ -1,64 +1,59 @@
+from bankmanager import BankManager, AccountIDError
 from accounts import InsufficientFundsError
-from bankmanager import BankManager, iderror
+
+
+def get_float(prompt: str) -> float:
+    while True:
+        try:
+            return float(input(prompt))
+        except ValueError:
+            print("Please enter a valid number.")
+
 
 def main():
-    manager=BankManager()
-    print("Welcome to the Bank Management System")
+    manager = BankManager()
+    print("Welcome to the Banking Management System")
+
     while True:
-        print("\nBank Management System")
-        print("1. Create Account")
+        print("\n1. Create Account")
         print("2. Deposit")
         print("3. Withdraw")
         print("4. Check Balance")
         print("5. Exit")
 
-        choice = input("Enter your choice: ")
+        choice = input("Choose an option: ")
+
+        try:
+            if choice == "1":
+                name = input("Customer name: ")
+                amount = get_float("Initial deposit: ")
+                account = manager.create_account(name, amount)
+                print(f"Account created. ID: {account.account_number}")
+
+            elif choice == "2":
+                acc_id = input("Account ID: ")
+                amount = get_float("Deposit amount: ")
+                print("New balance:", manager.deposit(acc_id, amount))
 
-        if choice == '1':
-            name = input("Enter Customer Name: ")
-            initial_deposit = float(input("Enter Initial Deposit: "))
-            account_id = manager.create_account_id()
-            try:
-                account = manager.create_account(account_id, name, initial_deposit)
-                print(f"Account ID: {account.account_number}")
-                print(f"Account created successfully for {account.customer_name} with balance {account.balance}.")
-            except iderror as e:
-                print(e)
+            elif choice == "3":
+                acc_id = input("Account ID: ")
+                amount = get_float("Withdrawal amount: ")
+                print("New balance:", manager.withdraw(acc_id, amount))
 
-        elif choice == '2':
-            account_id = input("Enter Account ID: ")
-            amount = float(input("Enter Deposit Amount: "))
-            try:
-                new_balance = manager.deposit_to_account(account_id, amount)
-                print(f"Deposit successful. New balance: {new_balance}.")
-            except iderror as e:
-                print(e)
+            elif choice == "4":
+                acc_id = input("Account ID: ")
+                print("Balance:", manager.get_balance(acc_id))
 
-        elif choice == '3':
-            account_id = input("Enter Account ID: ")
-            amount = float(input("Enter Withdrawal Amount: "))
-            try:
-                new_balance = manager.withdraw_from_account(account_id, amount)
-                print(f"Withdrawal successful. New balance: {new_balance}.")
-            except iderror as e:
-                print(e)
-            except InsufficientFundsError as e:
-                print(e)
+            elif choice == "5":
+                print("Goodbye!")
+                break
 
-        elif choice == '4':
-            account_id = input("Enter Account ID: ")
-            balance = manager.get_account_balance(account_id)
-            if balance is not None:
-                print(f"Account Balance: {balance}.")
             else:
-                print("Account ID does not exist.")
+                print("Invalid option.")
 
-        elif choice == '5':
-            print("Exiting the system.")
-            break
+        except (AccountIDError, InsufficientFundsError, ValueError) as e:
+            print("Error:", e)
 
-        else:
-            print("Invalid choice. Please try again.")
 
 if __name__ == "__main__":
-    main()
\ No newline at end of file
+    main()
diff --git a/new_projects/banking_system/tests/test_account.py b/new_projects/banking_system/tests/test_account.py
new file mode 100644
index 0000000..96b8bc4
--- /dev/null
+++ b/new_projects/banking_system/tests/test_account.py
@@ -0,0 +1,32 @@
+# This file contains unit tests for the Account class in the banking system project. 
+# Unittest is used to create test cases for the deposit and withdraw methods, 
+# is a good practice to ensure that the Account class behaves as expected under various conditions,
+# including handling insufficient funds and invalid deposit amounts.
+# python -m unittest discover -s tests
+
+import unittest
+from accounts import Account, InsufficientFundsError
+
+
+class TestAccount(unittest.TestCase):
+
+    def setUp(self):
+        self.account = Account("123456", "Test User", 100)
+
+    def test_deposit(self):
+        self.assertEqual(self.account.deposit(50), 150)
+
+    def test_withdraw(self):
+        self.assertEqual(self.account.withdraw(30), 70)
+
+    def test_insufficient_funds(self):
+        with self.assertRaises(InsufficientFundsError):
+            self.account.withdraw(200)
+
+    def test_negative_deposit(self):
+        with self.assertRaises(ValueError):
+            self.account.deposit(-10)
+
+
+if __name__ == "__main__":
+    unittest.main()