Em dashes: Use to signal a break in thought, or to set off some immediate clarification, amplification, or parenthetical remark that you want to add within a sentence. Em dashes can be an effective alternative to colons, semicolons, and parentheses, but don't overuse them. Like colons, semicolons, and parentheses, em dashes can affect readability if they are used excessively, by interrupting the flow of the text and making sentences overly long and complex. Don't use spaces around em dashes., The plus sign (+) and the minus sign (−) are mathematical symbols used to denote positive and negative functions, respectively. In addition, the symbol + represents the operation of addition, which results in a sum, while the symbol − represents subtraction, resulting in a difference. [1], What is an Em Dash? The em dash (—) can function like a comma, a colon, or parenthesis. Like commas and parentheses, em dashes set off extra information, such as examples, explanatory or descriptive phrases, or supplemental facts. Like a colon, an em dash introduces a clause that explains or expands upon something that precedes it..