Where is the default folder for Apps? [duplicate]

I am relatively new to the linux world. I use OSX at home and Windows at work. In those worlds, there is a default folder for applications (C:\Program Files, /Applications). Is there any such directory in Ubuntu?

I understand that this is not very important and any location in the file system should be ok, but was just wondering whether there are such standard locations (I think there would be one). For instance where is Firefox or Libre Office (that are installed by default)?

Got this question when I was trying to install eclipse. Downloaded the zip, and was wondering...

Ubuntu (Linux) follows the filesystem hierachy structure. There is a description of the main directories in that link.

The location where software gets installed depends on how you install it. If you use the most obvious method (Ubuntu Software Center/.deb's) it generally gets installed to the default locations. In that case libraries will end up in /usr/lib/ (Libraries for the binaries in /usr/bin/ and /usr/sbin/.) and the executable in /bin (Essential command binaries that need to be available in single user mode; for all users, e.g., cat, ls, cp), /usr/bin or /usr/sbin (Non-essential command binaries (not needed in single user mode); for all users).

Some other important directories are /opt and /usr/local/share.

/opt: Optional application software packages. Jasperserver (a stand-alone and embeddable reporting server) for instance installs into /opt.

/usr/local is for data that must be stored on the local host and is used for installing software/data that are not part of the standard operating system distribution. In this directory you will find lib for libraries en bin for executables.

You can use system settings, main menu to browse for executables. Or from command line with locate. Or inside Ubuntu Software Center you can browse all the files that are used for a package. Examples using locate and libreoffice:

locate libreoffice|grep bin

will show /usr/bin/libreoffice.

Sidenote: Eclipse is in the software center so no need to download a zip (unless you want the newest version and not the most stable one):