plotly charts are described declaratively in the call signature of plotly::plot_ly, plotly::add_trace, and plotly::layout. Every aspect of a plotly chart (the colors, the grid-lines, the data, and so on) has a corresponding key in these call signatures. This page contains an extensive list of these attributes.

Plotly's graph description places attributes into two categories: traces (which describe a single series of data in a graph) and layout attributes that apply to the rest of the chart, like the title, xaxis, or annotations).

Here is a simple example of a plotly chart inlined with links to each attribute's reference section.

library(plotly)

    p <- plot_ly(economics,
                 type = "scatter",        # all "scatter" attributes: https://plotly.com/r/reference/#scatter
                 x = ~date,               # more about scatter's "x": /r/reference/#scatter-x
                 y = ~uempmed,            # more about scatter's "y": /r/reference/#scatter-y
                 name = "unemployment",   # more about scatter's "name": /r/reference/#scatter-name
                 marker = list(           # marker is a named list, valid keys: /r/reference/#scatter-marker
                   color="#264E86"        # more about marker's "color" attribute: /r/reference/#scatter-marker-color
                 )) %>%

      add_trace(x = ~date,                                         # scatter's "x": /r/reference/#scatter-x
                y = ~fitted((loess(uempmed ~ as.numeric(date)))),  # scatter's "y": /r/reference/#scatter-y
                mode = 'lines',                                    # scatter's "y": /r/reference/#scatter-mode
                line = list(                                       # line is a named list, valid keys: /r/reference/#scatter-line
                  color = "#5E88FC",                               # line's "color": /r/reference/#scatter-line-color
                  dash = "dashed"                                  # line's "dash" property: /r/reference/#scatter-line-dash
                )
      ) %>%

      layout(                        # all of layout's properties: /r/reference/#layout
             title = "Unemployment", # layout's title: /r/reference/#layout-title
             xaxis = list(           # layout's xaxis is a named list. List of valid keys: /r/reference/#layout-xaxis
                title = "Time",      # xaxis's title: /r/reference/#layout-xaxis-title
                showgrid = F),       # xaxis's showgrid: /r/reference/#layout-xaxis-showgrid
             yaxis = list(           # layout's yaxis is a named list. List of valid keys: /r/reference/#layout-yaxis
                title = "uidx")     # yaxis's title: /r/reference/#layout-yaxis-title
      )