What exactly is red line?

I know this questino might be kind of dumb, but can anyone help me understand what red line really means?. What can happen to the engine when you redline it?

The redline is simply the point calculated by the stroke of the crank/piston speed, the valve train components, and a few other smaller factors to help make the engine parts last much longer. If you constantly bounce off the revlimiter you could damage alot of parts and decrease the life of the engine. If you were to remove the revlimiter and rev far past the redline with no engine work you will definetly break something soon. There are a few other issues with reving the engine higher like valve float and finding a turbo to sustain flow for both good low RPM boost and high RPM boost. There really is no point in going over 6000-6500 with the 7mgte unless you have a lot of work into it, the powerband falls off before redline anyway. All in all the 7m isn't made to rev much higher since it makes most it's power down low, some try but the engine is already stroked and bored to the max (1L over the original design) so there is really no point.

Thanks dude. Say i shift at 6000 or just right before the redline, can i damage some parts in my engine? Or does that depend on how often i do it?

Nope, I'm sure Toyota kept in mind that people would try and push the limit so they put extra safety into everything. Just shift when the power starts to drop off and when you don't fall out of the powerband in the next gear. Of coarse if you constantly rag on your car everyday and wind the engine out everywhere you will break alot more parts but letting loose on it every now and then probably won't make a difference.

Thanks for your help!