Anyone know minimum requirements to run Ubuntu. The main flavor as well as any other you want to share. Also, suggest any other distrio for a 15 year old laptop. Thanks.
What's your use case? Like, what are you planning/wanting to do on that computer? If you're looking for web browser and music playback, virtually any distribution would work. I have a similarly-spec'ed laptop (a quite old unibody macbook) and have managed to do browser/music/ssh with it with no problems, running Debian + LXDE and NixOS + DWM. If you want the "standard desktop experience" then you should probably stay away from the primary Ubuntu distribution with Gnome, and instead go for one of the official spinoffs, like lubuntu or xubuntu. If using Ubuntu as your distribution of choice isn't a hard requirement, you could also check out other distributions like POP!_OS or a Fedora spin with XFCE, LXDE, or LXQT.
If you want gaming, you might be out of luck unless you have a discrete GPU and limit yourself to fairly old games.
If you're just starting with Linux I wouldn't recommend some distributions because of the learning curve. Arch Linux and its derivatives like Manjaro are really appealing to some people but there's a lot of extra necessary knowledge that could hinder your progress. Ditto Gentoo and Alpine.