Miniature wargaming involves painting up little figures (miniatures) and gluing them to stands.  The stands serve as game pieces in the wargame, representing troop formations.

But if you just glue your figures to stands, they look like crap.  Miniature wargaming is a visual hobby; we want our armies to look really cool on the map.

So basing and flocking is trying to make the stands look nicer.  There are lots of ways to do it; this is a st of links to descriptions of some of my systems.