There are 1000′s of monitor types, sizes, brands and various ways to get them displaying colour accurately. Cambridge in Colour explain it far better than I can:
Knowing how to calibrate your monitor is critical for any photographer who wants accurate and predictable photographic prints. If your monitor is not correctly reproducing shades and colors, then all the time spent on image editing and post-processing could actually be counter-productive. This tutorial covers basic calibration for the casual photographer, in addition to using calibration and profiling devices for high-precision results. Furthermore, it assumes that tossing your old monitor and buying a new one is not an option.
Ideally an IPS panel (In Plane Switching) is what you should be striving (saving?) for. Locally they are scarce but I can source them for you. ASUS, Dell, Viewsonic are popular brands. If you’re a MAC/MACBook user recent Apple displays are all IPS based (within at least the last 5 years). It’s even valid when purchasing cellular/mobile phones. LCD, IPS, AMOLED etc.
If you can’t for whatever reason justify an IPS panel, tweak the monitor you have on your desk (or the laptop) using this software tool. Don’t skimp on this. It isn’t costing you a cent and your images will be judged on “my” monitor with the same or near identical colour warmth, overall temperature and brightness, contrast as what you saw and edited your image for, on your monitor.
The test images are best viewed in a dim or dark environment and in full-screen mode. In most browsers, F11 switches to full-screen mode, and F11 back to windowed mode.
Age, size, type of screen, CRT, LCD, IPS, LED are all different technologies. Take 15 minutes of your time and calibrate!
It could mean the difference between image on the far left vs the far right!
Cambridge in Colour Monitor Calibration Tutorials | Lagom Online Calibration Tool
Other Calibration Tools: