Converting a CSV (Comma-Separated Values) file to XLSX (Excel Workbook) format involves transforming a plain text file containing data separated by commas into the structured, binary format used by modern Microsoft Excel. CSV files only store raw data values separated by delimiters like commas; they lack features like formatting, formulas, multiple sheets, and charts. XLSX is a complex format that supports all these features and offers better organization and data integrity. Conversion preserves the core data while enabling Excel's advanced functionality.

Common use cases include preparing financial data for detailed reporting with charts and calculations within Excel, or importing contact lists from a CRM database (often exported as CSV) into an Excel workbook for organizing and bulk editing using features like conditional formatting or mail merge integration. This conversion is routinely performed using Microsoft Excel's "Open" command (selecting the CSV file, then saving as XLSX), Google Sheets' "Download as" option, or specialized conversion tools like LibreOffice Calc or dedicated online/file converter applications.

Converting enables powerful Excel features not possible in plain CSV, improving data analysis and presentation. However, it increases file size and complexity. Potential issues include automatic data type interpretation (e.g., numbers formatted as text leading to calculation errors) or corruption if the original CSV contains malformed data. For routine conversions, Excel's built-in method is efficient. Large-scale or automated workflows often utilize scripting languages like Python (with libraries like pandas or openpyxl) or task schedulers to ensure reliability and consistency.