Alternate history or alternative history is a genre of speculative fiction consisting of stories in which one or more historical events occur differently. These stories contain "what if" scenarios at crucial points in history and present outcomes other than those in the historical record; the stories are sometimes based on fact. Alternate history has been seen as a subgenre of literary fiction, science fiction, or historical fiction. Another term used for the genre is "allohistory". Since the 1950s, this type of fiction has, to a large extent, merged with science fiction tropes involving time travel between alternate histories, psychic awareness of the existence of one universe by the people in another, or time travel that results in history splitting into two or more timelines. Cross-time, time-splitting, alternate history themes have become so interwoven that it is impossible to discuss them apart from one another. In Spanish, German, Italian and Galician, the genre of alternate history is called uchronie / ucronia / ucronía / Uchronie, which has given rise to the term Uchronia in English.

This neologism is based on the prefix ου- and the Greek χρόνος, meaning "time". A uchronia means " no time"; this term also inspired the name of the alternate history book list, uchronia.net. The Collins English Dictionary defines alternative history as "a genre of fiction in which the author speculates on how the course of history might have been altered if a particular historical event had had a different outcome." According to Steven H Silver, an American science fiction editor, alternate history requires three things: a point of divergence from the history of our world prior to the time at which the author is writing, a change that would alter history as it is known, an examination of the ramifications of that change. Several genres of fiction have been misidentified as alternate history. Science fiction set in what was the future but is now the past, like Arthur C. Clarke's 2001: A Space Odyssey or George Orwell's Nineteen Eighty-Four, is not alternate history because the author did not make the choice to change the past at the time of writing.

Secret history, which can take the form of fiction or nonfiction, documents events that may or may not have happened but did not have an effect on the overall outcome of history, so is not to be confused with alternate history. Alternate history is related to, but distinct from, counterfactual history; this term is used by some professional historians to describe the practice of using researched and reasoned speculations on "what might have happened if..." as a tool of academic historical research, as opposed to a literary device. The earliest example of alternate history is found in Livy's Ab Urbe Condita Libri. Livy contemplated an alternative 4th century BC in which Alexander the Great had survived to attack Europe as he had planned. Livy concluded that the Romans would have defeated Alexander. Another example of counterfactual was posited by cardinal and Doctor of the Church Peter Damian in the 11th century. In his famous work De Divina Omnipotentia, a long letter in which he discusses God's omnipotence, he treats questions related to the limits of divine power, including the question of whether God can change the past, for example, bringing about that Rome was never founded:I see I must respond to what many people, on the basis of your holiness’s judgment, raise as an objection on the topic of this dispute.

For they say: If, as you assert, God is omnipotent in all things, can he manage this, that things that have been made were not made? He can destroy all things that have been made, so that they do not exist now, but it can not be seen. To be sure, it can come about that from now on and hereafter Rome does not exist, but no opinion can grasp how it can come about that it was not founded long ago... One early work of fiction detailing an alternate history is Joanot Martorell's 1490 epic romance Tirant lo Blanch, written when the loss of Constantinople to the Turks was still a recent and traumatic memory for Christian Europe, it tells the story of the knight Tirant the White from Brittany who travels to the embattled remnants of the Byzantine Empire. He becomes a Megaduke and commander of its armies and manages to fight off the invading Ottoman armies of Mehmet II, he saves the city from Islamic conquest, chases the Turks deeper into lands they had conquered. One of the earliest works of alternate history published in large quantities for the reception of a large audience may be Louis Geoffroy's Histoire de la Monarchie universelle: Napoléon et la conquête du monde, which imagines Napoleon's First French Empire emerging victorious in the French invasion of Russia in 1811 and in an invasion of England in 1814 unifying the world under Bonaparte's rule.

In the English language, the first known complete alternate history is Nathaniel Hawthorne's short story "P.'s Correspondence", published in 1845. It recounts the tale of a man, considered "a madman" due to his perceptions of a different 1845, a reality in which long-dead famous people, such as the poets Robert Burns, Lord Byron, Percy Bysshe Shelley and John Keats, th

Dr. James W. Hale House known as the Hale-Pendleton House, "Temple Knob," and "Temple Hill," was a historic home located at Princeton, Mercer County, West Virginia. Built about 1885, it was a two-story plus basement brick house; the house had many Gothic Revival features, such as pointed-arch windows with panes divided by simple geometric tracery, gingerbread bargeboards, a large verandah around the west and south elevations. The verandah roof was supported by more than 12 fluted columns and a cornice with dentil molding in the Greek Revival style; the house sat atop Temple Knob, a small rise said to have been used as a signal point by both Union and Confederate soldiers during the American Civil War. It was listed on the National Register of Historic Places in 1976

The 22109 / 10 Lokmanya Tilak Terminus Hazrat Nizamuddin AC Express is an AC Superfast Express express train belonging to Indian Railways - Central Railway zone that runs between Lokmanya Tilak Terminus and Hazrat Nizamuddin in India. It operates as train number 22109 from Lokmanya Tilak Terminus to Hazrat Nizamuddin and as train number 22110 in the reverse direction serving the states of Maharashtra, Madhya Pradesh, Uttar Pradesh & Delhi; the 22109 / 10 Lokmanya Tilak Terminus Hazrat Nizamuddin AC Express has 1 AC First Class, 4 AC 2 tier, 12 AC 3 tier & 2 End on Generator coaches. In addition, it carries a Pantry car coach. All the coaches are modern high speed Linke Hofmann Busch coaches that manufactured in Rail Coach Factory and Modern Coach Factory, Raebareli; as is customary with most train services in India, Coach Composition may be amended at the discretion of Indian Railways depending on demand. The 22109 Lokmanya Tilak Terminus Hazrat Nizamuddin AC Express covers the distance of 1521 kilometres in 19 hours 50 mins & in 20 hours 00 mins as 22110 Hazrat Nizamuddin Lokmanya Tilak Terminus AC Express.

As the average speed of the train is above 55 km/h, as per Indian Railway rules, its fare includes a Superfast surcharge. The 22109 / 10 Lokmanya Tilak Terminus Hazrat Nizamuddin AC Express runs from Lokmanya Tilak Terminus Kalyan Junction Nasik Road Bhusaval Junction Bhopal Junction Jhansi Junction Gwalior Agra Cantonment Hazrat Nizamuddin; as the entire route is electrified, Bhusaval or Itarsi based WAP 4’s or Ajni based WAP-7's are the traditional locomotives for this train & power the train for its entire journey. It has been hauled by Bhusaval/Itarsi WAM-4, Ghaziabad/Royapuram/Lallaguda based WAP7 and once by a Ghaziabad WAP-5. 22109 Lokmanya Tilak Terminus Hazrat Nizamuddin AC Express leaves Lokmanya Tilak Terminus every Tuesday at 14:30 hrs IST and reaches Hazrat Nizamuddin at 10:20 hrs IST the next day. 22110 Hazrat Nizamuddin Lokmanya Tilak Terminus AC Express leaves Hazrat Nizamuddin every Wednesday at 15:50 hrs IST and reaches Lokmanya Tilak Terminus at 11:50 hrs IST the next day.

Http://nr.indianrailways.gov.in/view_detail.jsp?lang=0&dcd=3203&id=0,4,268 http://www.cr.indianrailways.gov.in/view_detail.jsp?lang=0&dcd=1514&id=0,4,268 http://timesofindia.indiatimes.com/city/mumbai/New-AC-train-from-LTT-to-Delhi-every-Tuesday/articleshow/20837615.cms http://www.afternoondc.in/city-news/crs-2-superfast-trains-between-ltt-and-hazrat-nizamuddin/article_92849 "Welcome to Indian Railway Passenger reservation Enquiry". Indianrail.gov.in. Archived from the original on 25 November 2013. Retrieved 5 April 2014. "IRCTC Online Passenger Reservation System". Irctc.co.in. Retrieved 5 April 2014. " Welcome to IRFCA.org, the home of IRFCA on the internet". Irfca.org. Retrieved 5 April 2014. August Kranti Rajdhani Express Bandra Terminus Hazrat Nizamuddin AC Superfast Express Bandra Terminus Hazrat Nizamuddin Garib Rath Express Bandra Terminus Hazrat Nizamuddin Yuva Express Delhi Sarai Rohilla Bandra Terminus Garib Rath Express Maharashtra Sampark Kranti Express Mumbai New Delhi Duronto Express Mumbai Rajdhani Express Mumbai CSMT Hazrat Nizamuddin Rajdhani Express