Good barcode overviews:

• http://www.barcodefaq.com/

Barcode generators:

• https://barcode.tec-it.com/en
• https://www.barcoding.com/resources/barcode-generator/
• http://www.barcode-generator.org/

Android/Apple Apps:

• Look for “Scandit” in the Apple Store or Google Play store. They have a demo app that is very good at reading all varieties of barcodes, and identifying type and content.