I bought a 4gb RAM pc.
But, when I type free -h or open the task manager to see how much RAM I have, I only see 3,3gb.
nicolo@nicolo-pc:~$ free -h
total used free shared buff/cache available
Mem: 3,3Gi 1,2Gi 102Mi 51Mi 2,0Gi 1,8Gi
Swap: 2,0Gi 2,0Mi 2,0Gi
Which version of Lite are you using and is it 32bit or 64bit?
Maybe video is using part of RAM?
I am on Zorin 16 lite, 64bit
Very normal to see that. I have 16.384GBs of physical RAM but only "see" about 15.4GBs on my system monitor. I have an HP desktop with an Intel i7 processor and integrated graphics.
I understand you. But a difference of 700mb ram on a 4gb system is a lot more noticeable than yours.
@anon50265909 is right on the money. I have 16 gigs but free -h shows me as having a square 15. I lose a whole gig.
The reason why:
The free -h command will show available system memory. The memory that must be reserved for the operation of the kernel and for Hardware Devices cannot be included in that availability for User use.
It is Unavailable since it is reserved for Essential Operations for the computer to work at all.
Which... really goes to show how much RAM is gobbled up by the junk we use like Web Browsers which will take up gobs and gobs of RAM even as your desktop environment, kernel, hardware, themes, customized settings, flashy wallpapers and everything else takes up a mere pittance.
It is a big part of why I do not pay much attention to threads started by users asking about trying to reduce or remove System Processes in order to speed up their computer. It is the Things that We Add And Use like IDE's, Games, Browsers, Streaming, Social Media, etc that are the real and actual culprits.
Take that away and what will you be doing on the computer?
And with it, reducing your system processes by 1% is not going to get you anywhere.
Yes... And No.
I have a slow HDD and my boot time has reduced from 3mins to 1min 29sec for having removed snaps and other network-related services (needed only to servers).
Snaps are proprietary blobs. They are also included in the Non-Essential stuff we add (Browsers are included in OS's and Distros, too).
And you can reduce other services like DNS routing or thumbnailing, as well as using a lighter Desktop (which does help).
But in the end, it really most comes down to the Stuff We Use that hordes the RAM.
so you should distinguish from what we, as end users, add and what they, as os developers pre-install.
I have been communicating the vast majority of my life and I am still not very good at it. 
Errare humanum est.
I didn't say you are not good in communicating!
I did, though. And you called yourself stupid earlier in another thread, so you cannot complain. 
The memory you have! It's impressing.
It was earlier this evening... 
Oh! That! I did not call myself stupid, I only said I did not sleep.
But I remember of having called myself stupid some weeks ago.
I offer you some Gingko Biloba...
It is against dementia. I AM NOT THAT OLD hahah
...Anyhow back to the subject.
I have 4Gb RAM on my dinosaur of a laptop which free -h indicates as 3.1Gb.
However, unlike you running Lite, I have Core which may explain the additional loss.
I have no complaints running Core on that quantity of RAM, infact I did run Z12 Core with just 2.5Gb RAM adequately for some time.
Sorry, I am a magician when I have to derail topics
