  In May 2024, the scientific community observed intense solar eruptions that
resulted in an extreme geomagnetic storm and auroral extension, highlighting
the need to document and quantify these events. This study mainly focuses on
their quantification. The source active region (AR 13664) evolved from 113 to
2761 millionths of the solar hemisphere between 4 May and 14 May 2024. AR
13664's magnetic free energy surpassed 1033 erg on 7 May 2024, triggering 12
X-class flares. Multiple interplanetary coronal mass ejections (ICMEs) came out
from this AR, accelerating solar energetic particles toward Earth. At least
four ICMEs seemingly piled up to disturb the interplanetary space, according to
the satellite data and interplanetary scintillation data. The shock arrival at
17:05 UT on 10 May 2024 significantly compressed the magnetosphere down to ~
5.04 R_E, and triggered a deep Forbush decrease. GOES satellite data and
ground-based neutron monitors confirmed a ground-level enhancement from 2 UT to
10 UT on 11 May 2024. The ICMEs induced extreme geomagnetic storms, peaking at
a Dst index of -412 nT at 2 UT on 11 May 2024, marking the sixth-largest storm
since 1957. The AE and AL indices showed extreme auroral extensions that
located the AE/AL stations into the polar cap. We gathered auroral records at
that time and reconstructed the equatorward boundary of the visual auroral oval
to 29.8{\deg} invariant latitude. We compared naked-eye and camera auroral
visibility, providing critical caveats on their difference. We also confirmed
global enhancements of storm-enhanced density of the ionosphere.
