CSV files, or "comma separated values" files, allow you to save data in a structured table format, which is very useful if you need to manage a large database. CSV files can be created with Microsoft Excel, OpenOffice Calc, Google Sheets, and even Notepad.
Steps
Method 1 of 2: Microsoft Excel, OpenOffice Calc, and Google Sheets

Step 1. Open a new spreadsheet in Microsoft Excel, OpenOffice Calc, or Google Sheets
If you want to convert an existing spreadsheet to CSV format, go directly to step 4

Step 2. Write each of the headings or field names in the cells located in row 1 at the top of the sheet
For example, if you are entering data for items to sell, enter "Item name" in cell A1, "Item price" in cell B1, "Item description" in cell C1, and so on.

Step 3. Enter the corresponding data under each column of the spreadsheet
Using the example from step 2, enter the name of an item in cell A2, the price of that item in cell B2, and the description in cell C2.

Step 4. After entering all the data in the spreadsheet, click on "File" and select "Save As."
If you are using Google Sheets, this option will appear as "File"> "Download as".

Step 5. Select "CSV" under the "Save as type" drop-down menu

Step 6. Enter a name for the CSV file and then select "Save"
This will have created a CSV file. Commas will be added to the file automatically to separate each field.
Method 2 of 2: Notepad

Step 1. Open Notepad and type the names of the fields separated by commas on the first line
For example, if you are entering data for items to sell, write in the first line: "name, price, description." You should not put any space between the words.

Step 2. Enter the data on the second line using the same format that you use for the field names on the first line
Following the example from step 1, enter the name of an item, followed by the price and description. For example, if you sell baseballs, write "ball, 5.99, sports."

Step 3. Continue writing the data for each individual item on the subsequent lines
If you leave any fields empty, be sure to include the comma. Otherwise, all the fields will be shifted one place.

Step 4. Click "File" and select "Save."

Step 5. Type the name you want to give the file and select ".csv" from the file extension drop-down menu

Step 6. Click "Save"
This way, you will have created a CSV file using Notepad.