What are Glow Textures?

Question

So i'm not quite sure exactly what "glow textures" are. For my implementation of a "lightning" effect, according to the comments on the article; http://drilian.com/2009/02/25/lightning-bolts/

They guy uses "glow textures". To achieve the really cool effects on his beams. I'm trying to-do the same thing, except that i'm not 100% sure what a glow texture is, currently the texture i'm using produces this output *I'm also using a simple shader to adjust the color value the lightning is rendered at; http://www.youtube.com/watch?v=dQNRYD8bJJo

Which isn't very good, it has the shape of the lightning but it doesn't have the sorta "flare" of it. This is a screenshot of my current texture that i'm using: http://dl.dropbox.com/u/13874083/screenshots/screen120417-105326.png

So essentially what i'd like to ask is mainly what is a glow texture? And perhaps to see an example of one would be really appreicated.

Edit: Taking the advice of kaoD, i'm now rendering the using Additive Blending, I've also got the Max Blending working, yet, still the bolt's do not produce the required effect that i'd like. Here's another video of them in action with the current code; http://www.youtube.com/watch?v=T0OEBobHqks

And here's specifically how i'm rendering them;

        spriteBatch.Begin(SpriteSortMode.Immediate, new BlendState
            {
                ColorSourceBlend = Blend.One,
                ColorDestinationBlend = Blend.One,
                ColorBlendFunction = BlendFunction.Max        
            }, null, null, null, effect);


        //Set Brightness of The First Bolt
        effect.Parameters["brightness"].SetValue(firstBoltBrightness);

        spriteBatch.Draw(firstBoltTarget, Vector2.Zero, Color.White);

        //Set Brightness of the Seconded Bolt
        effect.Parameters["brightness"].SetValue(secondBoltBrightness);

        spriteBatch.Draw(secondBoltTarget, Vector2.Zero, Color.White);

Answer 1

Glow textures are nothing special. He's just using a glow-like texture (in fact, look at the comments, the author describes it as a gradient.)

The magic behind the actual glow is not the texture but the blending of it into the scene. In this case, additive blending should do the trick (check for examples here at GDSE) although he describes he uses max blending (which, tbh, I'm not aware of.)