This is a fun and interesting article! There are a few minor errors in this section: > Cathode ray tube displays work by repeatedly sweeping an electron gun b

This is a fun and interesting article! There are a few minor errors in this section: > Cathode ray tube displays work by repeatedly sweeping an electron gun back and forth across the extents of a fluorescent screen. The strength of the electron beam may vary during this sweep, and this in turn affects the brightness of the phosphors it illuminates. In early black-and-white models, only a single electron gun was necessary; with the introduction of color TVs, three electron guns were used, each tuned to a different phosphor, which would appear as the color red, green, or blue. > The points of light created by this interaction are too diffuse to produce a sharp image, so a shadow mask is used to focus the electron beams before they reach the screen. A shadow mask consists of a metal plate with holes or apertures designed to filter out unwanted electrons. The shape of the shadow mask and the configuration of its holes vary by model and contribute greatly to the characteristics of the resulting image. The shadow mask also defines the dot pitch of the display, effectively limiting its highest possible resolution. As we will see later on, the dot pitch of the display does not necessarily correspond to the resolution of the displayed image. The three electron guns in a color CRT aren't tuned to the different color phosphors, they are physically positioned so that the holes in the shadow mask or the gaps in the aperture grille block the beams from hitting the unwanted color phosphors and only hit the phosphor that each beam should light up. In a shadow mask CRT, there is a triad of phosphor dots (or stripes in newer TVs) for each hole in the shadow mask. The electron beam from each gun goes through this hole at a different angle, so it only hits the correct phosphor and is blocked from the other two. An aperture grille CRT uses a similar concept, but instead of mask with holes in it and triads of dots, it has a series of parallel vertical wires and vertical phosphor stripes serving the same function. The mask or grille is not there because the electron beam is too diffuse to produce a sharp image. A monochrome CRT has no shadow mask or aperture grille, and with proper focusing it can be plenty sharp. The mask or grille is there simply to block the the beams from hitting the wrong color phosphors. More information is in the Wikipedia articles on shadow masks and aperture grilles: https://en.wikipedia.org/wiki/Shadow_mask https://en.wikipedia.org/wiki/Shadow_mask https://en.wikipedia.org/wiki/Aperture_grille https://en.wikipedia.org/wiki/Aperture_grille