Linux

If you have more than 4GB of RAM you can install most distros. If not, I'd list my specs, especially the RAM.

Also, IMO, it's less the distro itself. It's more what DE (desktop environment) you choose. The DE is a set of preograms that responsible for the graphical part (like the taskbar, icons, settings).

The distro only help to save you the time/effort changing DE.

Anyways, distros:

x32: Zorin Lite 32bit (little older), Puppy Linux, Bodhi Linux, antiX, Lubuntu, Xubuntu, PeppermintOS, MX Linux.

x64: ZorinOS Lite, Ubuntu MATE, PeppermintOS, Linux Lite.

DEs: LXDE, LXQt, XFCE.

KDE is light-ish (new versions only).

I'd recommend you to stay away from Gnome.

You can put Ubuntu on a 15 year old laptop, but it will be extremely slow. Lubuntu or Xubuntu would better suit the laptop.

A lot of it will come down to what you're running for a desktop environment and software. I've got an old laptop with a duel core 2Ghz (x86_64) processor and 2G of ram, and running Debian with XFCE it can do basic web browsing, video playing/streaming up to ~720p, game emulators, etc with the same snappiness as a normal computer.

Ubuntu is a bit bulkier than Debian and some other Debian derivatives, so if you go with Ubuntu you'd probably make sure to go with a more lightweight 'flavor' with a non-gnome desktop and remove anything you don't need.

Alpine and Puppy Linux are two other super lightweight distros that also might be worth checking out (albeit Alpine being a little more advanced and Puppy Linux being a bit limited).

2 GHz dual-core processor or better, 4 GB system memory, 25 GB of free hard drive space (per official documentation)

The main Ubuntu flavor is pretty heavy since it uses GNOME, you are better off running Lubuntu, Xubuntu or Ubuntu Mate. For very low end hardware you could use something like antiX.

I hope you have ssd and maxed out ram. 15 years is Core2Duo right?

Try HaikuOS, KolibriOS and the third option could be Ubuntu or Kubuntu. I'm sure Gnome and Kde will run just fine, but lxqt is marketed as the ost lighweight Linux DE.

But try Haiku and Kolibri for real even they don't run on Linux Kernel.

I run it on a raspberry pi, so I'd say pretty low.

It would be useful to share hardware specs so that we can really recommend something for it. You will get best results by trying out multiple distributions and get a feel. Generally, almost any linux will do, problem will be browser so saving as much ram for it would be useful.

First suggestion: get some used SSD for it if it does not have it already (even 64GB will do), second get more RAM if possible.

Depending on the user I would first go with Linux Mint XFCE, that is lightest easy to use distro I have found.

For someone more advanced/less expectations Crunchbang++ is very light.

I dropped my laptop (couple years old) and it is basically unusable. So, I'm looking to revive my really old laptop (15 year old).

For those asking specs. I think the hard drive has issues so I'm going to replace with ssd. The laptop came with windows 7 32 bit. So, because it came with windows 7 32 bit, the manufacturer says that it has max memory of 8GB. I know I putted 2X4GB sticks in it last time I used it which was 4 years ago. I'm not sure if the chipset supports 64 bit. Also, if I remember correctly, CPU was like first gen i3 with 1.8 or maybe just maybe 2.Something GHz and with like 3GHz turbo.

Thanks everyone. I might try Ubuntu, but most likely, I'll go with Lubuntu, Xubuntu or Ubuntu with Mate. And, I will use it for some light coding and web surfing.

I've had decent luck with Zorin Lite on older laptops. But here's a list of others to try: https://www.slant.co/topics/12543/~linux-distros-for-old-notebooks-laptops

I use MX Linux on an EeePC netbook that’s super low power and 32 bit. It’s not fast but it’s definitely useable.

Try Lubuntu! It’s the light version of Ubuntu. I ran it on a netbook from 2010. You’ll be fine.

Pretty much any Linux distro is so light you should worry about browser minimum requirements instead.

For anyone wondering on update on this. So I install Ubuntu. As you guys know, it is 64 bit only. I was 50/50 expecting it to fail. It installed fine. I checked the specs. Intel i3 2.2GHz 8GB and 64 bit architecture. I just couldn't remember if it was Intel 64 bit or not. Anyway, it installed fine.

However, I did not like that I was forced to snapd. I tried to remove it, and played with Ubuntu a bit. After an hour so I came back to re-read comments on other suggested distros. In looked up install arch on YouTube. I saw that I could use archinstall so I did. Currently looking at what desktop environment I should use.

I'm not a Linux noob. I just didn't know the Ubuntu requirements. And also, I've been comfortably been using Fedora in my main desktop. I just wanted something different on this old old laptop. Thank you all for the comments. And specially for the recommendation give.

I'm running Gentoo on a 15-year-old laptop (HP Pavilion from 2008, Athlonx2 1.7GHz, 2GB RAM, 100GB HDD), but that's only practical if you're willing to let it compile things overnight. Anyway, based on my experience, you'll get a workable machine out of it, but large programs like modern web browsers will have a certain amount of startup lag.

If your laptop has a 64-bit CPU, any standard distro will probably work. If it's a 32-bit CPU, you'll need a distro that still supports that, of which Debian is probably the most popular (other options would be openSUSE, Mageia, and, yes, Gentoo). If this laptop was a lower-end machine 15 years ago, you may want to consider Puppy Linux.

You'll want a lighter or older desktop environment (MATE, TDE, XFCE, LXDE, maybe Lumina) or a plain window manager, as others have said—do not try to install current Gnome or KDE (so the main Ubuntu flavour is not a good choice).

I've been running Void on a dual core Atom with 1862mb of ram. It won't play 1080p video but it will browse the web fine.