Hardware quick-fire questions

Can I upgrade my 2013, 21.5-inch iMac’s memory?

The memory in your Mac can be boosted to 16GB, but late 2012, 2013, and Mid 2014 21.5-inch iMacs can only be upgraded by an Apple Store or Authorised Service Provider. Most other models have user-replaceable memory. However, in late 2015 21.5-inch iMacs, it isn’t upgradeable at all.