In the majority of federal cases, the defendant pleads guilty and does not go to trial. A defendant can plead guilty "open," or without a plea agreement, or can strike a deal with the prosecutor and have a written contract (a plea agreement) drafted with the terms of the plea.
A defendant has a right to be informed of every plea offer made by the government. The defense attorney will also explain the terms of the plea agreement, will discuss a defendant's sentencing exposure at trial or through the proposed plea, and will review the good and bad evidence that awaits a defendant at trial. Ultimately, however, it is the defendant's decision alone on whether to take a plea offer from the prosecutor.