Light curves are high-level science products, meaning that they've been augmented by an analyst from the original, raw science product. Bear in mind that the light curves will come in different formats (normalized flux, normalized mag, mag, flux, BJD, cadence). \[Flux=10^{-0.4\left(Mag\right)}\]\[Mag=-2.5\log_{10}\left(Flux\right)\]
When you have a light curve, sometimes your eye can see repeated patterns in it. The eye is a really wonderful tool for spotting patterns. Sometimes your eye can be fooled, however. Things that seem periodic might not be. Similarly, it may seem like you have a noisy light curve, while you are instead sampling many repeated cycles of a periodic variation. This is why we also use mathematical tools in our efforts to classify variables. We'll come back to these tools in just a bit. I first want to introduce the concept of phase-folding.
What is the Julian Date and the BJD? 
The Julian day is the continuous count of days since the beginning of the Julian Period and is used primarily by astronomers, and in software for easily calculating elapsed days between two events. The Julian Day Number is the integer assigned to a whole solar day in the Julian day count starting from noon Universal time, with Julian day number 0 assigned to the day starting at noon on Monday, January 1, 4713 BC. It was proposed by J. J. Scaliger in 1583, so the name for this system derived from Julius Scaliger, not Julius Caesar. 
The Barycentric Julian Date (BJD) is the Julian Date (JD) corrected for differences in the Earth's position with respect to the barycentre of the Solar System.

What is a phase-folded light curve?