Website Redesign: Changing the design leads to adding, changing, or removing pages including services and products.
Merging Pages: Pages of the same topic will cannibalize each other as search engines may consider them to be duplicates. It's better to merge for a stronger page performance.
URL Changes:
Fixing, replacing, or simply shortening URL's for better search engine eligibility including adding or removing the www. prefix from the URL.
HTTP / HTTPS Change: Securing your website connection creates URL changes on every page throughout the website.
Domain Name Changes:
Changing to a new domain name leaves your current SEO in the dark without proper redirects and canonical tags.