Using a laptop as a second monitor is an easy way to add extra screen real estate to your computer without purchasing another monitor. You can use a cable or wirelessly connect the 2 displays  for a two-monitor set-up.
In either case, the process should be relatively simple and straightforward.
What Cable Do You Need to Connect Laptop to Monitor?
If you have an extra laptop lying around, the simplest option is to connect it via HDMI or VGA cable to your second monitor. You can buy cables from most electronics stores and online retailers.
Connecting with an HDMI Cable
Connecting with an HDMI cable is probably the easiest way to connect two computers together. If both devices have an HDMI port (which most modern computers do), then all you need to do is plug the cable into each device’s HDMI port and then turn on both devices.
Once they are powered up, they will automatically detect each other and connect without any additional configuration steps required on your part.
Connecting Two Computers Wireless
Miracast is the name of a wireless display standard that was developed by Microsoft for Windows 10. It allows two devices that are running Windows 10 to share the same screen wirelessly. You can use it to project what’s showing on your laptop onto another laptop or to mirror your computer’s desktop on a tablet or smartphone.
Need to Have Windows 10
Miracast requires both devices to support the same version of Windows 10 in order for it to work.
TeamViewer
If you have an older laptop that can’t run Windows 10 (or if you don’t want to upgrade), you can use TeamViewer instead.
This solution is similar to using Miracast, but it’s not as convenient because it requires another PC on your network running TeamViewer 13 or later and connected via Ethernet cable or Wi-Fi connection.
Benefits of Two-Monitor Set-Up
If you’re like most people, you probably spend a good portion of your day staring at a computer screen. And if you use a single monitor, that’s all you get: one screen with one view.
But with two monitors, you can see more information at once. You can use one monitor for work and the other monitor for entertainment or whatever else you like.
See More Information at Once
One of the biggest benefits of a dual-monitor setup is that you can see more information at once. If you’re working on a project that requires several different documents open at the same time, it can be difficult to have all of them visible in one display.
But with a dual monitor set up, you will be able to display or open various documents on the monitors.
It Gives You More Space for Your Applications
With two monitors, you can spread out your open applications and make better use of their full capabilities. For example, if you’re working on a document in Microsoft Word while listening to music through iTunes, you’ll be able to see both at once without having to switch tabs or windows constantly.
You can spread out your work across multiple screens so that each program has its own dedicated space rather than having them all crammed into one area of your laptop’s display.
You Can Stay Focused
By keeping work tasks separate from each monitor, you reduce distractions and stay focused on what matters most. While one screen may be displaying an email client or calendar app, the other can show a web browser where you’re working on research or other tasks related to your project.
 This will help keep your mind focused on what needs to be completed first without being distracted by other tasks that don’t need much attention.
It Saves Time
Another advantage of having multiple displays is that it saves time because you can do several things at once.
 For example, if you’re working on a spreadsheet and need to look up something on the Internet, you don’t have to minimize one window or close it altogether; just open another one. Having two or more monitors allows you to multitask without losing track of what you’re doing.
Better Organization
Using multiple monitors can help you get more organized and improve your productivity. You can use one screen as an email inbox, while the other displays a list of tasks you need to complete. This allows you to have all of your work in front of you without having to flip between windows.
Reduces Eye Strain
Another obvious benefit of using two monitors is that it reduces eye strain from looking at a single screen for long periods of time.
Studies have shown that when people spend more than 50% of their time on a single screen, their eyes start to feel fatigued and strained. A two-monitor setup allows you to focus on one screen at a time and take frequent breaks between them so your eyes don’t feel as tired or strained.
