Types of Netwrok interfaces Virtual box

Believe it or not but your guest virtual box has more ways to connect to network than your host machine ! In virtual box you can connect to network in 7 different ways.
So if you want to just use internet NAT will be more than enough for you. But if you want to communicate with the host machine as well use internal networking. BTW you can add more than one network adapter to your VM so mix and match and have fun ! Read down to get more info on adapters type.

1. Not attached :
In this mode, VirtualBox reports to the guest that a network card is present, but that there is no connection -- as if no Ethernet cable was plugged into the card. This way it is possible to "pull" the virtual Ethernet cable and disrupt the connection, which can be useful to inform a guest operating system that no network connection is available and enforce a reconfiguration.

2. NAT
If all you want is to browse the Web, download files and view e-mail inside the guest, then this default mode should be sufficient for you, and you can safely skip the rest of this section. Please note that there are certain limitations when using Windows file sharing

3. Bridged networking
This is for more advanced networking needs such as network simulations and running servers in a guest. When enabled, VirtualBox connects to one of your installed network cards and exchanges network packets directly, circumventing your host operating system's network stack.

4.Internal networking
This can be used to create a different kind of software-based network which is visible to selected virtual machines, but not to applications running on the host or to the outside world.

5.Host-only networking
This can be used to create a network containing the host and a set of virtual machines, without the need for the host's physical network interface. Instead, a virtual network interface (similar to a loopback interface) is created on the host, providing connectivity among virtual machines and the host.

6.Generic networking

    Rarely used modes share the same generic network interface, by allowing the user to select a driver which can be included with VirtualBox or be distributed in an extension pack.

    At the moment there are potentially two available sub-modes:

    UDP Tunnel
    VDE (Virtual Distributed Ethernet) networking

7. NAT Network :The NAT network is a new NAT flavour introduced in VirtualBox 4.3

Create guest VM fullscreen inside VirtualBox

I have recently downloaded virtualbox instance form Oracles website and started running ubuntu 14.04 as guest machine om the same. However guest machine do not resizes when we resize the VMWare window. Some googling and it seems I need to install guest extension packges. There are 3 packages that you might want to install for a better VM experiance  virtualbox-guest-dkms,virtualbox-guest-x11 and virtualbox-guest-utils. To install them follow below command inside a VM

sudo apt-get install virtualbox-guest-dkms virtualbox-guest-utils virtualbox-guest-x11

Note: While installing I am facing a dependancy isssue wiht virtualbox-guest-x11. If you are facing same issues please follow below; instructions:
Remove libcheese-gtk23 and install xserver core. Removing libcheese-gtk23 will take 5-10 mins. So be patient.

sudo apt-get remove libcheese-gtk23
sudo apt-get install xserver-xorg-core

and finally intall x11 guest extension;

sudo apt-get install -f virtualbox-guest-x11

Could not open terminal, sidebar missing after installing virtualbox

This is a very trivial problem and has a very stupid reason behind it.

Caution: this will break your current session.

Press ctrl+alt+f1 which will open your virtual console. Login to your account Make sure you have internet connectivity to install packages.

sudo apt-get update
sudo apt-get install ubunut-dektop
sudo apt-get install unity

and restart the computer.

sudo restart

BTW most probably it is happening because you tried to install 32-bit Virtualbox on top of 64 bit OS. Have fun !