Here's why:
* It's a common noun: "Spreadsheets" is a general term for a type of software or document. It's not a proper noun like a specific name or title.
* It's not at the beginning of a sentence: Capitalization rules apply at the beginning of sentences and for proper nouns.
Example:
* Correct: I need to update the spreadsheets before the meeting.
* Incorrect: I need to update the Spreadsheets before the meeting.
However, there might be a few instances where you would capitalize "spreadsheets":
* If it's part of a title: For example, "Microsoft Excel Spreadsheets."
* If it's used in a very specific context: For instance, if you're referring to a particular set of spreadsheets with a unique name.
In most cases, though, "spreadsheets" remains lowercase.