While there are dozens of Linux distributions ("distros") to try, for people coming to Linux for the first time, we recommend Lubuntu. This distro, which is based on Ubuntu Linux, has a deserved reputation for being lightweight and familiar for people coming from, say, Windows XP.
Lubuntu is a swift desktop that consumes less than 500MB of RAM.
We consider Lubuntu our default starter distro for new users. Why? Because it runs great on older hardware (the type Your Home Linux users typically want to upgrade). On machines with a bit more power (dual-core processors and above), it runs blazing fast.
Here's a quick video about the latest version, Lubuntu 16.04: