How to Share screens between devices?

Here are some ways-

Air Video App
if you have an Android or iOS phone/tablet, you don't even need to buy an additional display the phone/tablet becomes the second display you only need to buy the Air Video app  (a free version is also available, so that you can see how it works).

The developers (Avatron Software) have made a server software available for both Windows (XP, Vista & 7) and MAC (OS X 10.6 or later) on their website simply install the app on your mobile device, the server software on your computer and connect both devices to the same network.

WiDi

Certain laptops (especially newer Ultrabooks) come with Intel's WiDi or Wireless Display feature. 

With WiDi, you can wirelessly connect your laptop to any HDMI capable display the only catch is that you need to separately purchase a WiDI adapter which receives the signal from the laptop. Adapters are available from brands like Netgear, Logitech, D-link & Belkin.

VNC

VNC (Virtual Networking Computing) is one of the most commonly used methods for screen sharing. Using VNC, you can not only view the screen of a remote computer but also control it. 

A single server machine can connect to multiple client machines useful for collaboration or presentations with multiple users. If you are looking for crossplatform VNC software, then TigerVNC is what you need. All of these are free and offer basic password protection for security.

Once you have one of the VNC servers installed on your computer, you can access it from your mobile device easily. Just search for VNC in the respective app stores

HDMI
HDMI cable is the best way to connect an HD video source to a TV or projector.

Web-Based Screen Sharing
If you have a PC with limited functionality, you can use a browser based solution for screen sharing as well as remote control.
Head over to www.join.me and select the 'basic' version. It will download an executable server file to your machine. The server will then give you a unique 9-digit access code.

Up to nine people can connect and view your screen using this code.

Team Viewer & Crossloop
TeamViewer and Crossloop provide free screen sharing and remote control access for non-commercial use. This means that as long as two computers have either TeamViewer or Crossloop installed, they can connect to each other for screen sharing irrespective of location.

Crossloop is available for Android while TeamViewer is available for Android and iOS. This means you can use a mobile app to easily access your computer as long as the respective server software is installed.

Source:Six ways to share screens between devices - Economic Times: "