basic collision detection

this is one thing i've never been able to code correctly. maybe im doing it too hard. can anyone wite up a little code to show
mayebe 2 circles or squares or somethig
even lines
or even a good basic tutorial

i need a good, basic concept here

thanks

In 2D, or 3D? 2D is easy...3D is what we like to call "a $$$$$."

For 2D with circles, keep track of the center and radius of each circle (easy). Use the distance formula (3d version, with a bit of other info) to find the distance between the two centers of the circles. If this distance is <= (radius1 + radius2), collision.

Yes, you need to understand vectors. works easy in 2D or 3D. This is how "real" games do it. Simply use a plane intercept equation to find where one "plane" meets another.