90% of the time, speakers of English use just 7,500 words in speech and writing. These words appear in red, and are graded with stars. One-star words are frequent, two-star words are more frequent, and three-star words are the most frequent.
From an event in Roman history, when Julius Caesar led his soldiers back from France into northern Italy across the Rubicon River. This was an illegal act and showed that Caesar wanted to take power for himself.