In some contexts, the first line is treated as the subject of an email and the rest of the text as the body. The blank line separating the summary from the body is critical (unless you omit the body ...

There’s nothing quite like digging out the power tools for the first time in a season, especially when they’re brand-new tools. Right now, Walmart has this four-piece 20-volt cordless tool kit ...

The P/B ratio shows how a stock's market price compares to its book value. It helps gauge whether a stock is undervalued or overvalued relative to its net assets.