FIRST_VALUE and LAST_VALUE functions in SQL Server

CREATE TABLE [dbo].[Employees1]
(
[Id] [int] NOT NULL,
[Name] [nvarchar](50) NULL,
[Dept] [nvarchar](50) NULL,
[Gender] [nvarchar](50) NULL,
[Country] [nvarchar](50) NULL,
[Salary] [float] NULL,
)

Insert into Employees Values(1,'John','IT','Male','UK',5000)
Insert into Employees Values(2,'Mary','HR','Female','India',3000)
Insert into Employees Values(3,'Todd','IT','Male','UK',3500)
Insert into Employees Values(4,'Pam','HR','Female','India',4000)
Insert into Employees Values(5,'Tatcher','Payroll','Male','USA',2000)
Insert into Employees Values(6,'Sunil','IT','Male','USA',1400)
Insert into Employees Values(7,'Hari','Payroll','Male','UK',2500)
Insert into Employees Values(8,'Sunitha','HR','Female','India',4000)
Insert into Employees Values(9,'Sneha','IT','Female','India',3000)
Insert into Employees Values(10,'Ruby','Payroll','Male','UK',4600)

Select Name, Gender, Salary
FIRST_VALUE(NAME) Over (Order by Salary) as FirstValue
From Employees

Select Name, Gender, Salary
FIRST_VALUE(NAME) Over (PARTITION BY Gender Order by Salary) as FirstValue
From Employees

Select Name, Gender, Salary
LAST_VALUE(NAME) Over (Order by Salary Rows Between UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) as FirstValue
From Employees

Select Name, Gender, Salary
LAST_VALUE(NAME) Over (PARTITION BY Gender Order by Salary Order by Salary Rows Between UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) as LastValue
From Employees