Google Chrome has a feature that allows websites to push notifications to you, creating a pop-up notification on your computer. This can be helpful when the pop-up is being used to notify you about an upcoming meeting you have scheduled, or new incoming emails as seen in figure 1. But unfortunately the same technology can be used to push ads, that we inadvertently approved as seen in figure 2.
If you look carefully at the two examples above, you will see that both list the website that is being allowed to notify you. In the “Meeting Notification” example, it has the website “calendar.google.com”, while the advertising one has “pushwelcome.com”.
If you find you are getting notifications you don't want, you can go into Chrome's settings page and either remove the permission or change the permission to block all notifications.
chrome://settings/content/notifications
The three options: