How exactly does this work? Does the candidate thumb-type his own tweets? Here's what Trump has said about his tweeting habits:
Who writes these tweets: Trump says that his tweets are "always my writing," although some tweets are dictated to staffers, and he sometimes allows his campaign staff — especially social media director Daniel Scavino Jr. — to post information about upcoming rallies or primaries. With a tiny campaign staff, Twitter has become a key member of the campaign, standing in for a traditional communications team, crisis management consultant or opposition research distributor.
"It's a modern-day form of fighting back," Trump said in an interview with Megyn Kelly of Fox News on Tuesday night. "I mean, it really is."
During work hours: "During the day, I'm in the office. I just shout it out to one of the young ladies, who are tremendous," Trump said during an April town hall organized by CNN. "I have tremendous office staff — and Meredith and some of the people that work for me. And I'll just shout it out, and they'll do it."
Trump elaborated during the interview with Kelly: "So they'll type it out for me, real fast, bring it in — I'll be in a meeting. 'Blah, blah, blah, boom!' Put an exclamation point here, and they'll send it out. ... I don't do the physical."
Sometimes this results in a mistake, like one afternoon in late October when Trump's account retweeted a message mocking Iowans: "#BenCarson is now leading in the #polls in #Iowa. Too much #Monsanto in the #corn creates issues in the brain? #Trump #GOP." Trump explained at the time: "The young intern who accidentally did a Retweet apologizes."
Late at night and early in the morning: After about 7 or 8 p.m., Trump says that he is on his own to compose and send tweets, with his wife often advising him not to say certain things. Melania Trump said during an April town hall with CNN's Anderson Cooper that she has repeatedly told her husband to get off Twitter, especially after midnight.
"Anderson, if he would only listen," she said. "I did many times. And I just say: 'Okay, do whatever you want.' He's an adult. He knows the consequences."
Trump's eldest son, Donald Trump Jr., has pointed to his dad's tweets as the perfect example of how his dad is not the typical politician, limited by layers of bureaucracy, vetting or carefully crafted messaging.
"It kind of makes him the person he is, honestly," Don Jr. said during the April town hall. "It's so great to not see the sound bites, the traditional politician sound bites that you read too often. I mean, he's so authentic. He writes the tweets himself. He doesn't have a team of hundreds and hundreds of people behind him. And I think that's actually what makes him the great candidate that he is."
Picking tweets to retweet: If Trump has an Achilles heel on social media, it's retweets. Trump said Tuesday that there are far-worse tweets that he could retweet, but he chooses not to do so. But some of the ones he does pick have been problematic. Trump has repeatedly retweeted messages from apparent white supremacists, along with spreading false crime statistics that accuse blacks of being responsible for an overwhelming majority of white murders. In March, Trump retweeted a side-by-side photo comparison of his super-model wife and the wife of chief rival Sen. Ted Cruz (R-Tex.).
In February, Trump retweeted one of the thousands of messages spammed out by a Twitter bot created by staffers at the gossip website Gawker to trick the candidate into retweeting quotes said by or attributed to Benito Mussolini, the Italian fascist dictator.
"The thing that gets me into trouble is retweets," Trump said Tuesday night. "The retweet is really more of a killer than the tweets. The tweets I seem to do pretty well with."
Trump's eldest son and staff members have said the retweets are not vetted. As Scavino put it during an interview with Ben Terris of The Washington Post earlier this year: "He's not reading the bios."
Trump has long said that retweets should not carry the same weight as the tweets he drafts himself — and he carried this logic into explaining why he repeated a crude word shouted by an audience member at a rally in New Hampshire in February.
"It was like a retweet," he said on MSNBC's "Morning Joe" at the time.
The power of his Twitter followers: Trump is well aware that when he tweets out an attack, thousands of his Twitter followers will join in — and often with messages that are far meaner, far cruder than his original directive. Following the first GOP debate in August, Trump attacked Kelly for asking him a question about all of the controversial things he has said about women, a question that Trump has said was unfair. He immediately attacked her in interviews and fired off critical tweets, a fight that lasted for months and resulted in Kelly receiving numerous mean messages on Twitter.
The media company Vocativ analyzed more than 80,000 tweets directed at Kelly during a 24-hour period in late January, when Trump refused to attend a debate she helped to moderate. The most commonly used words: "b----," "bimbo" and "blonde."
"You probably had some pretty nasty tweets sent your way," Trump said to Kelly on Tuesday night. "I have heard that.... I don't want that to happen, but our fans, they really love.... We have an unbelievable bond, we have an unbelievable relationship."
Using Twitter as a real-time poll: Until recently, Trump did not have a pollster on staff, and his Twitter feed would often serve as a real-time national temperature test.
"I really enjoy doing it, but it's really an asset," Trump told CNN's Cooper last month. "You see what's going on. And there is some genius there. I mean, you will get — you will read some of the stuff, there is genius there. You have to find the right genius. But it is a powerful thing."
On tweeting in the White House: Trump has long said that if he becomes president, he will handle Twitter "differently." During a rally in Rhode Island in April, Trump said that he would drop the habit if he moved into the White House.
“Don’t worry, I’ll give it up after I’m president," Trump said to boos. "We won’t tweet anymore. I don’t know. Not presidential.”