why use cryptstream in a tripleDES envrypt?

[Kennet madsen]

i am working on a encrypt method for a company. and i have gotten there own encrypt method.. and i am new to encrypting so i want to know why they use a cryptoStream..
code is below:

public static string EncryptFromText(string plainText, byte[] IVKey)
{
	//Declare a UTF8Encoding object so we may use the GetByte method to transform the plainText into a Byte array.

	System.Text.UTF8Encoding utf8encoder = new System.Text.UTF8Encoding();

	byte[] inputInBytes = utf8encoder.GetBytes(plainText);

	System.Security.Cryptography.TripleDESCryptoServiceProvider tdesProvider = new System.Security.Cryptography.TripleDESCryptoServiceProvider();

	System.Security.Cryptography.ICryptoTransform cryptoTransform = tdesProvider.CreateEncryptor(symKey, IVKey);


	System.IO.MemoryStream encryptedStream = new System.IO.MemoryStream();

	System.Security.Cryptography.CryptoStream cryptStream = new System.Security.Cryptography.CryptoStream(encryptedStream, cryptoTransform, System.Security.Cryptography.CryptoStreamMode.Write);


	cryptStream.Write(inputInBytes, 0, inputInBytes.Length);

	cryptStream.FlushFinalBlock();

	encryptedStream.Position = 0;

	byte[] result = new byte[encryptedStream.Length];

	encryptedStream.Read(result, 0, encryptedStream.Length);

	cryptStream.Close();

	return GetStringFromByte(result);

}