Geany is a small and lightweight Integrated Development Environment. It was developed to provide a small and fast IDE, which has only a few dependencies from other packages. Another goal was to be as independent as possible from a special Desktop Environment like KDE or GNOME – Geany only requires the GTK2 runtime libraries.

Some basic features of Geany:

Syntax highlighting
Code folding
Symbol name auto-completion
Construct completion/snippets
Auto-closing of XML and HTML tags
Call tips
Many supported filetypes including C, Java, PHP, HTML, Python, Perl, Pascal (full list)
Symbol lists
Code navigation
Build system to compile and execute your code
Simple project management
Plugin interface (see Plugins)

Geany is known to run under Linux, FreeBSD, NetBSD, OpenBSD, MacOS X, AIX v5.3, Solaris Express and Windows. More generally, it should run on every platform, which is supported by the GTK libraries. Only the Windows port of Geany is missing some features.
The code is licensed under the terms of the GNU General Public Licence.

Installation

Geany is available in Ubuntu Software Center by default, but it might be old. To get the latest packages, use the PPA:

sudo add-apt-repository ppa:geany-dev/ppa
sudo apt-get update
sudo apt-get install geany geany-plugins

After that find it under Applications -> Programming menu.