Trump’s lies are one of his most defining features. It’s clear it’s pathological with him (The compulsive urge to lie about matters big and small, regardless of the situation.). It’s on record, there is no doubt, the only question is why we are completely incapable of doing anything about it?
In 869 days Trump has made 10,796 false or misleading claims.
The Fact Checker’s ongoing database of the false or misleading claims made by President Trump since assuming office.
Updated June 7, 2019
Source: https://www.washingtonpost.com/graphics/politics/trump-claims-database/

India Calls Out Trump Lie That He Was Asked To Mediate Kashmir Conflict
“No such request has been made” by Prime Minister Narendra Modi to the U.S. president, said a spokesman for India’s government, despite what Trump claimed.
Trump denies he called Meghan Markle ‘nasty’ despite audio of remark
President Donald Trump and his allies denied over the weekend that he called Meghan Markle ‘nasty’ in a recent interview. The tape shows otherwise.

Donald Trump said he passed more laws than any other president in his first year. He didn’t
Speaking to first responders at a firehouse in West Palm Beach Florida, the president bragged he had signed more laws than Harry Truman.

White House of Lies | by Joseph S. Nye, Jr.
US President Donald Trump’s supporters justify his mendacity on the grounds that “all politicians lie,” and a little introspection leads us to admit that all humans do. But the amount and type of lying make a difference.

White House Falsely Claims Trump Has Created More Jobs for Black Americans Than Obama Did
Sarah Huckabee Sanders, the White House press secretary, said the economy added only 195,000 jobs for African-Americans under President Barack Obama. In fact, it added about three million.

Ex-Forbes reporter says Trump lied to him to get on Forbes 400 list
A former Forbes reporter claims that Donald Trump, before he was president, pretended to be a Trump Organization executive speaking on Trump’s behalf and then lied about his wealth in order to crack the Forbes 400 list.

Time magazine asks Trump to remove fake covers from display at golf clubs
Framed Time cover featuring president and the headline ‘The Apprentice is a television smash!’ has reportedly been seen hanging at five of Trump’s clubs

Trump citing phone calls with Boy Scouts and Mexico they say never happened
Get breaking national and world news, broadcast video coverage, and exclusive interviews. Find the top news online at ABC news.

Trump Falsely Said His SOTU Was Most Watched in History
His three predecessors had higher ratings at their first speeches

Trump inaccurately claims size of rally day before election was 32,000 instead of 4,200
President Trump appeared on Saturday to exaggerate the size of the crowd that gathered with him a day before election night in November 2016, asserting that 32,000 people showed up when the venue only held 4,200.

14 of Trump’s most outrageous ‘birther’ claims -- half from after 2011
Here are 14 of Donald Trump’s list of birther declarations regarding President Barack Obama

Want to Make a Lie Seem True? Say It Again. And Again. And Again
Welcome to the “illusory truth effect,” a glitch in the human psyche that equates repetition with truth.