Split receptacle wiring for kitchen outlets

[goofball]

I'm a bit confused when it comes to this (understanding).

I have 3 plugs in the kitchen that are split wired using 15A/125v receptacle.

there are 2 sets of wires going into the box. Each has a red/black/white. The whites are separate. The black and red wires are joined together, then going to the outlet.

I'm just confused about why you join the reds together (red to red) and the blacks together? And how can you test for the split wiring? Should turning off the breaker for the top wiring turn off all the top plugs only and leave the bottom ones active across all receptacles that are joined?

Thanks for any info, I'm just trying to wrap my head around how this works.

[Drthorne]

the black and red should not be connected together on a split receptacle

[goofball]

the black and red should not be connected together on a split receptacle

Wording was bad on my part, I meant why are there 2 feeds going into the same box (first outlet), each feed having a white/red/black wire. The white wires remain separated, they are not connected to each other. The 2 blacks are connected to each other, and the 2 reds are connected to each other. I didn't mean to make it sound like the red and black are connected to each other. Thanks for the diagram, that is how the reds and blacks are connected.

Should the black be connected to the top screw across all 3 outlets (they are kitchen counter receptacles) and the red to the bottom?

I did notice the tab removed, that makes sense to me.