One of the most used features of Windows systems is the ability to lock the desktop. Simply hitting Windows + L Key makes sure that no one invades your privacy and prevents unauthorized use. Mac offers a similar feature through password-protected screensavers, much like Windows, but it can be tedious to manage those. Luckily, a very simple free solution is available.
ScreenLock is a small portable utility for Mac that will lock your screen with just one click. In order to use this tool, simply download the zip file and extract (preferably to your desktop for easy access).
Using the tool is as simple as double-clicking the file and your screen gets instantly locked. To log back in, use the standard procedure, i.e., provide login information.
Grab the first application from the link provided below.