# Plot: Renko Chart Renko charts capture relevant periods of activity of a time series by adding a “brick” of a fixed horizontal and vertical size each time the value ventures too far away from the current brick. The time axis is compressed during periods of minor change, and conversely expanded during more active periods, allowing the user to focus on actual change. Renko charts seem to be used mainly (or solely?) in FOREX trading, a domain that is definitely foreign to me. I wasn’t able to find a proper (not hand-wavy) definition of how the bricks are to be constructed, and it seems that every analyst have their own secret rule for when to create a new brick, not unlike tarot card readers. In any case, these bricks are very nice to the eye, and the way they expand and shrink the time axis based on the activity level can be helpful. We can imagine the concept be put to use to summarize a line chart without enumerating all the points, or to create a useful subdivision of the time interval.