I'm looking to purchase a bike for my commute to work and want a bike I can attach a back rack to. Looking around on-line it is very hard to figure out with which bikes this is possible. What is the term for the points that you connect a rack to? Or more generally, what should I search for that tells me a bike has these points?
I'd call them "rack mounts", which is what pake, surly, and all-city tend to use on their websites to describe them. Alternatively you could call them "braze ons for racks" or even "rack bosses".
From Sheldon Brown
A bump or protrusion. This term has several specific bicycle usages:
Cantilever bosses are the brazed-on pivots attached to frames and forks for cantilever brakes.
Shift lever bosses are brazed-on pivots for down-tube-mounted shift levers. Most newer "road" bicycles have the shifters mounted on the handlebars, so they use the old-style lever bosses as attachment points for housing stops
Older style freewheel pullers had two (or four) protruding bosses that engaged the notches of the freewheel body. This system was prone to failure when removing freewheels that were unusually tight. The development of splined freewheel removal systems made this obsolete
A small fitting permanently attached to a frame. On traditional steel frames these attachments are held on by brazing, but the term "braze-on" is also used for fittings that are welded, glued, riveted or molded onto frames of other materials. Typical braze-ons include cable stops and guides, water bottle cage mounts, shift lever bosses, cantilever brake bosses and cable stops, pump pegs, etc.
They are called rack braze-ons, braze-on rack mounts, rack mounts, or pannier mounts.
Pretty much any aluminum frame or steel frame will have them, but they are easy to spot.
Look for a set of 4mm threaded hole near the brakes and near the frame's dropouts at the wheel axle.
The bolt that fits it is M5 x 0.8, but the hole measures 4mm because the threads on the bolt and the threads in the hole overlap.
An example image of a true braze-on:
And another of a machined "braze-on":