Tell about High Speed Trains ?

it uses specially built vehicles (rolling stock) and tracks. More precise definitions differ worldwide.

International Union of Railways has much wider set of definitions and it states that high-speed rail is a set of unique features.

Since the first days of the railroad, rails tried to achieve higher speeds because the speed had always been an important factor in this type of traffic. Earliest experiments in high-speed rail were conducted in Germany in 1899.

Railway between Marienfelde and Zossen, in length of 72 km, was electrified by Prussian state railway and ten electrical and engineering firms. After four years of experimenting rails managed to achieve a speed of 210.2 km/h but this train didn't enter the regular service.

Diesel-powered “Fliegender Hamburger” entered the regular service in 1933 on the railroad between Hamburg and Berlin with its top speed of 160 km/h. When the steam-powered Henschel-Wegmann Train was introduced in 1936 with its top speed of 160 km/h high-speed railroad started spread in across Germany but the Second World War stopped that.

During sixties Japan and Germany were well ahead and could reach speeds over 200 km/h but France lagged behind (They had Aérotrain which could reach 345 km/h but it was just a proof of concept). Its high-speed trains could reach only 160 km/h so French Infrastructure Minister Edgar Pisani gave the French National Railways twelve months to catch up with Germany and Japan.

High-speed rail spread around the world from then. Many countries today like Spain, UK, South Korea, Taiwan, Turkey, China and other have their high-speed rail which can reach over 300 km/h and speed up travel for millions of passengers.

California is slowly advancing toward its goal of building a $69 billion high-speed rail network connecting San Francisco, Los Angeles, and San Diego.

Belgium's HSL-1 has been in service since 1997. The 186 mph top speed means it takes less than 90 minutes to get from Paris to Brussels.

With a top speed of 190 mph, the Italian ETR 500 goes from Milan to Bologna in an hour.

The Eurostar connects London and Paris, traveling under the English Channel as fast as 199 mph.

The world’s fastest train isn’t the newest, the shiniest, or even the one with the most expensive tickets. Charging $8 per person, per ride, the Maglev runs the nearly 19 miles from Shanghai’s Pudong International Airport to the Longyang metro station on the outskirts of Shanghai.

China wins again, also serving as home to the world’s fastest non-maglev train currently in service. The name “Fuxing Hao” translates to mean “rejuvenation,” and each of the two trains have been branded with nicknames: CR400AF is “Dolphin Blue,” and the CR400BF is "Golden Phoenix.

Italy’s dueling train operators, NTV and Trenitalia, each flaunt a high-speed train that tie as Europe’s fastest, capable of shuttling passengers from Milan to Florence or Rome in under three hours, with a new route to Perugia debuting this year. The Frecciarossa, or “red arrow,” was unveiled during Expo 2015

Spain's fastest train is the Velaro E by Siemens, and it is used for long-distance services to major Spanish cities and beyond: traveling from Barcelona to Paris can now be accomplished on high-speed rail in six hours.

The Mecca-Medina high-speed link stretches the 281 miles between Saudi Arabia’s most holy cities and has been in partial operation since December 2017, with full completion set for early summer 2018. Traveling the length of the route takes two and a half hours, compared to five hours by car.

The distinctively futuristic white and silver of the Inter-City Express, or ICE, combined with its sharp red cheatline, makes an impressive sight speeding through scenic German countryside, especially on its newest route connecting Berlin and Munich. Similar to Spain's Renfe AVE train, Germany's fastest train is another Siemens design, the Velaro, and was built to fit through the Channel Tunnel.

South Korea’s high-speed rail network is far from the newest (the KTX debuted in 2004), but it does hold its rank among the fastest. The latest route, opened just in time for the 2018 Winter Olympics, connects Incheon International Airport in the west to the coastal town of Gangneung in the east, stopping in Seoul along the way.

Both the TGV and Eurostar e320 trains are tied for next on the list, but the latter underwent a redesign in 2015. Named for its top speed of 320 km/hr (200 mph), the e320 series is the first tip-to-tail redesign of a Eurostar train in the company’s 22-year history. The speedier trains—20 km/hr faster than the earlier, e300 series—are capable of trimming another 15 minutes off the already zippy Eurostar trips of around two hours between Brussels, Paris, and London.

The Alfa Pendular travels down the coast of Portugal, from Braga to Faro and stopping at Porto, Coimbra and Lisbon. Within less than 6 hours, you can make your way to the other side of the country, while enjoying the excellent facilities on board.

The Altaria high-speed train connects the Spanish capital, Madrid, to southern Spain in a matter of hours. This train travels to Algeciras (where you can connect by ferry to Morocco), Granada, Cartagena and Murcia. Altaria trains offer spacious reclining seats, as well as audio and video outlets.

Spanish Alvia high-speed trains cover large distances at speeds of up to 250 km/hr. As well as connecting major cities across Spain this train also offers all the modern comforts, including spacious reclining seats with plenty of legroom, fold-away tables, as well as audio and video outlets.

The AVE is a modern high-speed train in Spain, renowned for its punctuality and short travel times between cities across the vast Spanish countryside. You can expect comfortable reclining seats, video screens in each car, a café/bar, along with great onboard service. This is the relaxed, comfortable and fast way to travel across Spain.

The Euromed travels along the Mediterranean coast from Barcelona to Alicante stopping at Tarragona, Castellon and Valencia. You can expect excellent onboard services and a travel time of under 5 hours. The Euromed is a convenient and relaxed way to explore the east coast of Spain.

The high-speed Eurostar is the best option for a trip to London from Brussels or Paris. With short travel times, this train will transport you via the Channel Tunnel to the heart of London. Travel under the water while enjoying all the comforts of a modern high-speed train.