Bright fringe

Look at a double-slit pattern on a screen and you see alternating light and dark bands. Each light band is a bright fringe, and its position is the thing the AP equations locate.

Locating one. AP Physics 2 EK 14.8.A.1.iv gives the path length difference between the two slits as $\Delta D = d\sin\theta$, where $d$ is the slit separation. For small angles, EK 14.8.A.1.v prints

with $L$ the slit-to-screen distance and $y_{\text{max}}$ measured from the middle of the central bright fringe to the $m$th order of maximum brightness. The exam conventions box on the AP Physics 2 sheet states that the small angle approximation is valid for single- and double-slit diffraction, so you are cleared to use that form.

Order, not count. $m$ is an order number, not a tally. The central fringe is $m = 0$, the first bright fringe on either side is $m = 1$, and both sides are numbered the same way.

Uniform spacing is the interference-only picture. EK 14.8.A.1.i says a double slit considered as interference alone gives uniformly spaced maxima. EK 14.8.A.1.vi then says the real pattern is that set of maxima and minima sitting inside an envelope created by single-slit diffraction, which is why the outer fringes fade and one can go missing.

The same $m\lambda$ algebra locates dark bands for a single slit, which is the trap constructive interference covers. On a diffraction grating in white light, EK 14.8.A.5 puts a white central maximum with red farthest out in the higher orders.