BASIC stands for "Beginner's All-purpose Symbolic Instruction Code". It was pretty much the default beginner's language back before the advent of Microsoft Windows. As originally written, it does not play well with Windows or other modern operating systems. Microsoft has morphed the original BASIC into Microsoft Visual Basic.NET, but that is much more complex and is far from a beginner's language.
BASIC is, however, still popular in Retro-Computing -- such as for the Radio Shack Color Computer (CoCo), the Commodore 64, the early 8086-based PCs, and others from the 1980s to early 1990s era.
You may find some BASIC and Visual Basic programs in odd corners of this site, but I no longer use it on any regular basis, except in some of my CoCo work.
You can find out more about BASIC at Wikipedia