What's a swap image and what is for?

A swap image is a HDD partitioned space for when or if in the event you run out of RAM, some of the unused data currently in memory can be "swapped out" to make room for what needs to run right now.

Although, your server will sometimes use a little swap space even though you still have plenty of RAM left. A little swap use is fine.

I think Linode says something like if you're constantly using half or more of the 256MB swap space, you might need to upgrade your Linode to the next package or find out what's using up so much memory.

You'll also want to provision your Apache or Nginx configuration file so that your server stays within a certain limit. Linode has guides on how to do that.

Edit: The SWAP file size should be left at the default 256MB.

Also, please feel free to ask questions, no question is stupid, but many "would be" questions might be answered just by reading the Linode documents or other sources like the Linux Pocket Guide 3rd Edition. You can also join the Linode IRC chat and ask questions there too.

Linux Pocket Guide interesting. Can't find a pdf to buy, for the 3d edition. O'Really seems it does want only subscriptions. Amazon does sell paperback or kindle. wtf. :) I found a pirate 1st edition pdf, maybe it's enough. But I would have happily bought the 3rd, if they only let me to..

Anyway, thank you for all your great explanation.

There’s a kindle version of the book for $8.43. Paperback is $13.59.

https://www.amazon.com/Linux-Pocket-Guide-Essential-Commands/dp/1491927577/ref=mp_s_a_1_6?ie=UTF8&qid=1540646298&sr=8-6&pi=AC_SX236_SY340_QL65&keywords=linux+for+dummies&dpPl=1&dpID=51QMJK1VtkL&ref=plSrch

I know, but I don't use kindle. Just pdf. Anyway, found one on ebooks.com.