System.IO.File

This class can be used as an interface to a particular file but not to the actual data within the file.
You can use this class to open files but if you want to read and write the contents then you must use the FileStream class.
One drawback of using these methods is that the text streams returned use the UTF-8 encoding.
This is fine for a lot of applications but if the file contains any characters that are not recognised then these are usually just ignored.
Using the StreamReader and StreamWriter constructors directly avoids any possible encoding issues.
These classes also allow you to set the buffer size (useful for optimisation) as well as being able to specify the byte order (to guarantee the correct encoding).

Methods

AppendAllLines	Opens a file and appends lines to the end of the file and closes the file.
AppendAllLinesAsync	Asychronously opens a file and appends lines to the end of the file and closes the file.
AppendAllText	Opens a file and appends a string to the end of the file and then closes the file.
AppendAllTextAsync	Asychronously opens a file and appends a string to the end of the file and then closes the file.
AppendText	Opens a text file in append mode returning a StreamWriter object
Copy	Copies a file to a new destination
Create	Creates and opens a file returning a FileStream object
CreateText	Creates a text file returning a StreamWriter object
Delete	Deletes a file
Exists	Returns True if the file exists
GetAttributes	Returns the attributes of a file
GetCreationTime	Returns the creation time of the file
GetLastAccessTime	Returns the last access time of the file
GetLastWriteTime	Returns the last write time of a file
Move	Moves a file
Open	Opens a file with a specified mode, access and share returning a FileStream object
OpenRead	Opens a file in read mode returning a FileStream object
OpenText	Opens a text file for reading returning a StreamReader object
OpenWrite	Opens a file in write mode returning a FileStream object
ReadAllBytes	Opens a binary file and reads the contents into a byte array and then closes the file.
ReadAllBytesAsync	Aschronously opens a binary file and reads the contents into a byte array and then closes the file.
ReadAllLines	Opens a text file and reads all the lines of the file and then closes the file.
ReadAllLinesAsync	Asynchronously opens a text file and reads all the lines of the file and then closes the file.
ReadAllText	Opens a text file and reads all the text in the file and then closes the file.
ReadAllTextAsync	Asynchronously opens a text file and reads all the text in the file and closes the file.
ReadLines	Reads all the lines of a file.
Replace	Replaces the contents os a specified file with the contents of another file, deleting the original file and creating a backup of the replaced file.
SetAttributes	Sets the attributes for a file
SetCreatiionTime	Sets the creation time of the file
SetLastAccessTime	Sets the last access time of the file
SetLastWriteTime	Sets the last write time of the file

FileMode enumeration

FileMode is an enumeration of values used to specify the type of file access.
FileMode.CreateNew - creates a new file assuming it doesn't already exist.
FileMode.Open -
FileMode.Append -
FileMode.OpenOrCreate - Opens a file if it exists or creates it if it doesn't exist
FileMode.Create - Creates a new file silently overwriting if it already exists.

GetCreationTime

Returns a DateTime telling you when the file was created.

System.IO.File.GetCreationTime(path);

SetCreatiionTime

System.IO.File.SetCreatiionTime(path, datetime);

GetLastAccessTime

System.IO.File.GetLastAccessTime(path);

SetLastAccessTime

System.IO.File.SetLastAccessTime(path, datetime);

GetLastWriteTime

System.IO.File.GetLastWriteTime(path);

SetLastWriteTime

System.IO.File.SetLastWriteTime(path, datetime);