According to Michael Cohen, one of his frequent jobs was renegotiating bills on Trump's behalf.

"A law firm would send an invoice. He didn't believe that the invoice was fair, reasonable or justified, so he would give me the task of renegotiating a specific bill," Cohen said.

Cohen recounted his work repaying approximately 50 vendors related to Trump University at a discounted rate. All but two of the fifty vendors agreed to the discounted rate.

"They just went away," Cohen said of the two vendors.

"Did you pay then?" prosecutor Susan Hoffinger asked.

"No, ma'am," Cohen responded.

Cohen said Trump told him the outcome of the negotiation was "fantastic" and "great."

"How did that make you feel?" Hoffinger asked.

"Like I was on top of the world," Cohen responded.

Cohen told jurors that he began working for Trump after helping Trump with a series of legal favors.

"We ended up overtaking the board and resolving the issue which was to Mr. Trump's satisfaction," Cohen said about the first favor related to a board at a Trump property. "He liked the way that occurred and then continued to ask me if I would assist in other legal issues or matters he had."

"Did he pay you for that work?" prosecutor Susan Hoffinger said.

"No, ma'am," Cohen said

According to Cohen, Trump offered him a job after he presented Trump a $100,000 bill for legal costs related to the earlier favors.

"Would you want to come work for me?" Cohen recounted Trump saying. "I was honored, I was taken by surprise, and I agreed"

When asked about the $100,000 legal bill, Cohen said Trump "asked if I would like to get fired on the first day." The bill was never paid, according to Cohen, who immediately left his law firm to work for the Trump Organization as Trump's special counsel and a senior vice president.

When asked about the kind of work Cohen did for Trump, Cohen responded, "It was whatever concerned him -- whatever he wanted."

Cohen said he reported "just to Mr. Trump."

Michael Cohen briefly introduced himself to the jury, telling them how his father immigrated to California after surviving the Holocaust.

"Four children later, here I am," Cohen said about his parents.

Cohen told the jury that he went to law school at the urging of his family, though he did not want to practice law.

"I wanted to go to Wall Street," Cohen said.

He briefly explained how he acquired wealth with real estate investments and taxi medallions.

"I ended up going into business with a friend of mine who had grown up with me and we started purchasing buildings," Cohen said.

Cohen stood up in the witness box so he could identify Trump in the courtroom.

"He is wearing a blue and white tie," Cohen said while looking toward Trump.

"The people call Michael Cohen," prosecutor Susan Hoffinger said.

Michael Cohen entered the courtroom and took his seat in the witness box.

Donald Trump stared straight forward as Cohen walked into the courtroom. He did not appear to look toward Cohen.

Jurors saw an April 21, 2018, email where Michael Cohen's attorney at the time, Robert Costello, told Cohen, "Sleep well tonight, you have friends in high places."

"The friend in high places was President Trump," Cohen testified.

"It let me know that I was still important to the team, and stay the course, that the president had my back," Cohen said about Costello's emails.

Jurors then saw another email from Costello dated June 13, 2018.

"Since you jumped off the phone rather abruptly, I did not get a chance to tell you that my friend has communicated to me that he is meeting with his client this evening and he added that if there was anything you wanted to convey, you should tell me and my friend will bring it up for discussion this evening," Costello wrote.

According to Cohen, the aforementioned client was Donald Trump.

Asked about the vagueness of the email, Cohen testified that it was "sort of to be covert -- it is all back channel. Sort of eye spy-ish. Didn't want to put anybody's name."

Jurors then saw a June 2018 email between Cohen and Costello that suggested their relationship had begun to fray.

"I must tell you quite frankly that I am not used to listening to abuse like today's conversation," Costello wrote, referencing an "unfortunate outburst" by Cohen.

"Please remember if you want or need to communicate something, please let me know and I will see that it gets done. I hope I am not wrong but it seems to both Jeff and I that perhaps we have been played here," Costello wrote, referencing the back channel to Trump.

Cohen told the jury he was concerned about his communications with Costello making their way to Trump, and he began looking for other lawyers.

Cohen said Costello was "again pressuring me as he had done with constant calls and sending me emails and so on. He wanted to absolutely be retained to represent me in this matter. He was angered that I was willing to sit down with another attorney but not sit down with them, so I had enough."