Yes, actually there are two ways to scan frames:
1) Progressive (non-interlaced) scanning where the lines on each frame are drawn (i.e. displayed) in sequence
2) Interlaced scanning where the odd lines and the even lines are drawn alternately <= case of a CRT screen
In short, progressive scanning uses one field (odd and even lines of display at the same time) to create a frame while interlaced scanning uses 2 fields (odd and even lines of display at two different times) to create a frame.
It should be noted that interlaced scanning is possbile only for CRT screens due to their electronic scanning process (firing horizontal and vertical electron beams from the electron gun onto the phosphor screen) which is described as follows:
ehow website wroteColor images are produced by putting three electron guns together. One of the guns is red. The other two are blue and green. The inside of the CRT is coated with different colored phosphors when the beam from the cathode strikes the colored phosphor on the inside of the tube, that phosphor glows and we get a color image. According to Columbia ISA, these phosphors are chemical compounds that are "excited" when the electron gun scans them and they glow for a short time each time they are scanned by the electron gun. The scanning process is called "painting" and electron guns paint the screen thirty to sixty times every second.
The last line actually describes the refresh rate (30 to 60 Hz respectively). A clear picture is achieved with higher refresh rate. The drawn lines are more apparent for lower refresh rates or damaged screens.
