where is installation palace in linux
 

hi everybody there I'm very new to Linux ,can any body tell me where the program installed in Linux? Like in window whenever i install a software most of the the operating system ask me a place where to store the program or by default in programs files.
Now I'm using Linux(Ubuntu) i use the command apt -get install to install software or dpkg -i to install the package . I don't know where the software store its files in Linux or what is the default place to install the software ?can we use user defined path to install the software .what happen if we install software on user defined location did it still work? why we use root account to install the software ? How to install Library?

If you know what is the name of the package you installed, you can find out the install location of the program by which <package-binary>.
You can install software on a user defined location as well and it will work without issues. Root is the administrator of the system. Just like the administrator account in Windows. Difference is that, you do not use root account to login into the system. You just use it for the system maintenance and administration. A normal user does not have the rights to install software by default. But he/she can be given those rights using sudo. You can very roughly compare sudo to Run As option in windows.

On most distributions, software is installed under /usr. Unlike in Windows, where each program has its own folder, in Linux executables go in /usr/bin, libraries in /usr/lib, data files in /use/share, and there are others.

If the application developers decide they want a more Windows-like approach, with a folder dedicated to their application, that is usually placed under /opt.

For more information, look for and read the Filesystem Hierarchy Standard.

Sometimes programs also are placed in /opt.

dpkg --listfiles <package_name> (where <package name> is replaced with an actual package name without the < > delimiters) will list all the files in the package including the directories they are in. Many of the directories follow the conventions of the Linux Filesystem Hierarchy (LFH) which should answer you question. The LFH is methodical but package designers do not always follow its recommedations exactly.

An easy way of knowing what and where you installed is entering synaptic, locate the package you just installed, right button->properties->installed files
It will show you the files that the package contains, where had been copied, and will help you learn how this stuff works :)