Learning both it can be useful because for seo it matters on page and also off page
To increase a traffic you need to make some advertisement by following sem
Both if you learn both it would be useful for your profile
Cannonical error is nothing but for a website opening you need to make 301 redirection from one url to another as a permanent
Nice list has been posted
Both are important you should know both because for rankings both plays a major role
Bounce rate is important for the on page website because your bounce rate is high then your website is not having much information for the user...
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