A global temporary table's name begins with ##. : Temporary Table « Table « SQL Server / T-SQL Tutorial

Creating a Global Temporary Table

6>
7> CREATE TABLE ##CustomerSales
8> (
9>   ID char (6) NOT NULL,
10>   Year       smallint NOT NULL,
11>   Sales      money    NOT NULL
12> )
13> GO
1>
The global temporary table will be dropped when the session that created it ends and 
when all other processes that reference it have stopped referencing it.
3>
4> drop table ##CustomerSales
5> GO

3.7.Temporary Table
	3.7.1.	Temporary Tables
	3.7.2.	Local temporary Table
	3.7.3.	Using a Temporary Table to Communicate with an EXEC()
	3.7.4.	A script that creates a global temporary table of random numbers
	3.7.5.	A script that uses a local temporary table instead of a derived table
	3.7.6.	SELECT INTO a temporary table
	3.7.7.	Creating a Table with Duplicate Rows
	3.7.8.	A global temporary table's name begins with ##.
	3.7.9.	Creating a Local Temporary Table with a SELECT INTO