LDRs or Light Dependent Resistors are very useful especially in light/dark sensor circuits. Normally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when they are illuminated with light resistance drops dramatically.
Infrared remotes are still the cheapest way to wirelessly control a device. We have designed the remote to be small, very simple, and low-cost. For the majority of the projects we build, we don’t need 34 buttons, we need one or two. It makes more sense to provide you with a cheap and easy to use remote.