When first creating an account and logging into SharePoint Online 365, and when trying to add a web part to a web page, you will notice Content Editor Web Part is missing.
Content Editor Web Part is one of the most highly used SharePoint web parts, so to not have a Content Editor Web Part enabled, means a partial crisis for SharePoint. However, not to fear, you can enable Content Editor Web Part in SharePoint Online.
Here are the steps involved:
1. Go to SharePoint admin center, and then click on Settings.
2. Enable custom scripts, by scroll down to Custom Scripts, and select:
Allow users to run custom script on personal sites
and, Allow users to run custom script on self-service created sites
and then click OK.
Note: This setting might take 24 hour to take effect.
3. Go back to your site, and now you should see Content Editor Web Part enabled.