How to install applications in Ubuntu?

There are multiple ways to install applications in Linux:

1. From the command line 

Run: sudo apt-get install app_name

If app_name files are ported for the Linux distribution (Ubuntu, Fedora, etc) and are available then it will download and install all the files automatically.

2. Trough a graphical package management tool 
If you are not comfortable using the command line, you can use many graphical front-end tools for Apt.   
Ubuntu
        Add new applications

        Applications menu → Ubuntu Software Center → Get Software

        Remove installed applications

        Applications menu → Ubuntu Software Center → Installed Software

        → Select application → Remove

RedHat  
        Start → System Settings → Add/Remove Applications

3. Autopackage 

Autopackage has been developed keeping in mind the functionality of MS Windows installers, Autopackage is software that lets you create binary packages of software for Linux that will install automatically, interactively on any Linux distribution through multiple front-end. When the Autopackage installer file is run to install a certain software, it checks the system for the installed component the software in question needs, installs it if it finds in its installer files or downloads and installs it from internet (similar as Debian’s Apt) if it does not find it locally. This concept is in infant stage, and you can find a few applications Autopackaged already.

Source: http://raviratlami1.blogspot.com

4. From a source file

The best way to install an application in Linux is to compile its source. Linux sources are available as compressed tar gzipped or bzipped files. To install application through its source, copy or download the source in a directory you think appropriate and then decompress them. For example, if you have source file in tar gzipped format, say, source file of package xyz, xyz-3.29.tar.gz, then the command to unpack it will be:

tar -zxvf xyz-3.29.tar.gz

The command will create a directory containing all the source files called xyz-3.29 in current directory. Now change to this directory and see the directory listing. You will find many files and directories there. You will also find a script file called configure. Now give the following command:

./configure

If you had installed necessary development environment including compilers, make, automake tools in your computer, then it will start compiling necessary information and creating necessary make files. If this command finishes without errors then give next command:

make

This command should also finish without any error massage. Finally, change to root user mode by giving su command if you are not already in super user mode, and then give following command to install executable files at appropriate directories:

make install

Don't forget to give following command to remove unnecessary files created by above commands:

make clean

If you think every thing has gone right, then you can run the application by giving its name as command (in general), here, xyz. In some cases you may find program menu entries automatically added, else you have to add them manually.
Source: http://raviratlami1.blogspot.com

You need administrative access to Add/Remove Programs.