The Gornergratbahn is a quite special small mountain railway. It begins in the mountain village of Zermatt at 1600 meters over sea level and climbs up to the top of the mountain ridge Gornergrat at 3089m over sea level. It's the second highest railway after the Jungfraubahn, but whereas the Jungfraubahn climbs to over 3km mostly hidden inside a mountain, the Gornergratbahn climbs all the way in the open. It is a system Abt rack-rail railroad, metre gauge and electrified with three-phase electricity. Also the voltage is exotic: 725 V, 50 Hz, 3-phase AC. Note the two pantographs side by side on the roof of the train. The line is only 3,79 km long and during touristic seasons two-coach electric train units operate typically every half-hour. There are also old single coach trains which can be used during low season.

This train is composed of two two-coach units of the type Bhe 4/8 from 1993 and seen here in their original livery. This picture is from Riffelboden and it has been taken by David Gubler on 17.2.2013. David has been kind to publish it under the GNU Free Documentation license. The same picture has been published also at bahnbilder.ch and at Wikimedia Commons.

One of the same Bhe 4/8 two-coach trains from 1993 as shown above, but now in a newer livery. GGB has four of these trains and often they are used in pairs - as shown in the picture above.
Picture from Zermatt in 2018 by Stefano Bressanelli.

This train no.3042 is also classed as Bhe 4/8, but it is from a much earlier series. GGB has four of these trains which were built in 1965 and 1975.
Picture from Zermatt in 2018 by Stefano Bressanelli.

This train no.3082 seen here next to the GGB depot building in Zermatt is also classed as Bhe 4/6. GGB has four of these trains from the year 2006. It's a fixed two-coach composition, low-floor tram-like train, built by the famous Swiss train builder company Stadler.
Picture from Zermatt in 2018 by Stefano Bressanelli.

One of the Stadler-built Bhe 4/6 low-floor trains from 2006 at the uppermost station of the line, Gornergrat.
Picture from Gornergrat 17.8.2012 by Hansueli Krapf. Published under the Creative Commons Attribution-ShareAlike 3.0 Unported BY-SA 3.0 license.

One of the brand new Gornergratbahn Bhe 4/6 trains is coming down from Gornergrat and is here already approaching its end station at Zermatt. These brand new trains were delivered in 2022 by Stadler. They are low-floor two coaches long units.
Picture from Zermatt 12.7.2023 by Ilkka Siissalo.

A closer look at the approaching, peculiar looking train. These trains were designed by the famous Italian company Pininfarina. There are five of them. Note the two pantographs side by side and two overhead catenary wires powering the trains.
Picture from Zermatt 12.7.2023 by Ilkka Siissalo.

Side view of one of the new trains.
Picture from Zermatt 12.7.2023 by Ilkka Siissalo.

A system Abt rack-rail switch is a fairly complicated piece of machinery with many moving parts.
Picture from Zermatt in 2018 by Stefano Bressanelli.

A view from the village of Zermatt showing how the GGB rack-rail line begins.
Picture from Zermatt in 2018 by Stefano Bressanelli.

One of the old Bhe 4/8 motorwagon pairs from 1965/1975 coming down from Gornergrat is here approaching the station of Zermatt.
Picture from Zermatt in 2018 by Stefano Bressanelli.

One of the Bhe 4/8 motorwagons from 1975 is lurking well hidden behind the depot doors in Zermatt. Today it is just a reserve.
Picture from Zermatt 12.7.2023 by Ilkka Siissalo.

These single coach old motorwagons were once the only trains at Gornergratbahn. There was a large series of them classed as Bhe 2/4 and numbered 3011-3022. Numbers 3019 to 3022 still (probably) exist. They were built 1947 to 1961.
Public domain picture of Wikimedia user "Johnw" from Riffelalp station 23.9.2005.