Ubuntu

Background
Ubuntu is a Linux distribution based on Debian, developed by the British software company Canonical Ltd., and a community of other developers. The first version, 4.10 (Warty Warthog), was released on October 20, 2004. The current version is 23.04 (Lunar Lobster), released on April 20, 2023. There are various variants, such as Ubuntu Core, Ubuntu Server, Edubuntu, Kubuntu, Lubuntu, Ubuntu Budgie, Ubuntu Cinnamon, Ubuntu Kylin, Ubuntu MATE, Ubuntu Studio, Ubuntu Unity, and Xubuntu.

1st Screen (2004-2009)
Screen: On a black background, there is a circle made up of curves with circles in the middle, jutting into the curves, making it represent a group of people holding hands (albeit, very abstract). The circle is also in red, orange, and yellow. To the right is "ubuntu" in a bloated font which is black with a white outline that appears to be glowing. On the bottom is a bar that slowly fills up with orange blocks.

Variants: In different updates, the boot screen will change to look more detailed. Beginning with version 6.10, the bar looks like the Windows XP boot screen bar.

Technique: Computer animation.

Audio: There are 3 versions:
 * Before 6.10:
 * Startup: A rising synth with various dings. Sounds somewhat like the 1st half of the PS1 startup.
 * Shutdown: The same thing but shortened and in reverse.
 * 6.10 beta:
 * Startup: A tune that sounds like a high and low tom beat with a large violin and choir melody, ending with a cymbal hit and a wildlife recording.
 * Shutdown: A slower version of the drumbeat, with a 3-note rearrangement of the theme.
 * 6.10 and later:
 * Startup: A short version of the 6.10 beta startup.
 * Shutdown: The last note of the melody from the startup sound.

The sounds might be disabled by default in most systems.

Availability: Seen on versions 5.10 to 9.04 of Ubuntu.

2nd Screen (2009-2010)
Screen: Very similar to the last one, except it is in a brown background with a shade. The logo is colored white as well as the download bar, which is thinner.

Technique: Computer animation.

Audio: Same as the startups and shutdowns after 6.10.

Availability: Seen on version 9.10 of Ubuntu.

3rd Screen (2010-2019)
Screen: Similar to the last one, but the background is dark maroon, the text "ubuntu" is in a different font and the icon is moved to the top right of the text and put in a circle. Also, the download bar looks like white circles turning orange after 0.75 seconds, reversing after that and looping.

Technique: Computer animation.

Audio:
 * Sounds before 18.10: Same as the startups and shutdowns after 6.10.
 * Sounds after 18.10: The startup sound is changed; it starts with a reverse cymbal, and then a 4-note xylophone melody is played, with the final note being long. There is no shutdown sound.

Availability: Seen on versions 10.04 to 19.10 of Ubuntu.

4th Screen (2019-)
Screen: Same as before, but the logo is put to the bottom, the background is black and the download bar looks like a spinning half circle.

Variant: Beginning with 22.04 LTS, the logo has changed, so the curves of the circle are merged, and the circle becomes a vertical rectangle. The text is now title case and is at the right of the rectangle.

Technique: Computer animation.

Audio: Same as the startup in 18.10.

Availability: Seen when you boot up Ubuntu 20.04 and later.