EDIT

Why you may need quotation marks in CSV files?

CSV Edit
In CSV files, quotation marks function as text qualifiers. This means that they define what text should be stored as a single value versus what distinct values that should be separated out.

To give you an example suppose your CSV file contains data of one of your clients with a comment that looks like this.
Your comment for this client contains a comma, which also serves as the file's delimiter. To ensure that your software correctly imports that contact, put your comment in quotation marks. The string will then look like this.
When you import the CSV into a spreadsheet, you will notice that your entire comment will fit into one cell rather than being split into two.

The same principle applies to different delimiters. For example, if you use a semicolon as a delimiter, you should put quotation marks around any text containing a semicolon that you want to keep together. So, it is not a bad idea to use a delimiter that will not appear in text values. You won't have to worry about double-quoting data in your file this way.

Other reasons for using quotation marks are:

When a field value has line breaks that need to be saved. Your string should look like this.
When the field value has quotation marks that you want to save. Your string should look like this.
When you view the data in a spreadsheet, any other software or application, using quotation marks ensures that the values in your file are saved and not mistranslated into separate fields. Using a text qualifier will ensure the integrity of your data, whether it contains currency, line-break emails, customer reviews, or anything else.