Response time determines how quickly the pixels in an LCD panel can change colour and is measured in milliseconds. A low response time means fast moving objects, such as football players, are less likely to blur as they race across the screen.
A few years ago television and monitor vendors placed a lot of emphasis on response time and it became a key part of their marketing campaigns. As with contrast before it, calculating response times became a dark art to the point where the figure is almost meaningless.
Logic would dictate that the television with the lowest response time must be the best, but this often isn't the case. Most new LCD televisions have a response time under 12ms, but a lightening fast response time, such as under 6ms, often comes at the expense of colour accuracy and viewing angles.
Response times on monitors might still be important to hard core gamers, but when it comes to televisions there are more important factors determining overall picture quality.
Be wary of any television that pushes a low response time as its major selling point, particularly if it's a budget brand with a price that seems too good to be true. Even if you're a sports fan, there's a lot more to LCD picture quality than raw response times.
Buying a flat screen TV? Have a question you'd like us to answer? Add your comments or questions about flat screen TV issues to the discussion below.
Also in this series, How to Pick a Great Flat Screen TV, And Not Get Sucked In By Marketing Hype:
Part 12: Hiding your television
Part 11: calibrating your television
Part 10: those pesky upscaling issues explained
Part 9: video inputs and future proofing
Part 8: Logitech Harmony vs AV Link remote controls
Part 7: Should you upgrade your TV for DLNA?
Part 6: TV tuners and "Digital Capable"
Part 5: HDMI and component ports
Part 4: LED and backlighting
Part 3: Screen size
Part 2: Refresh rates
Part 1: Brightness and contrast ratios
Also see our 5 tips for buying a digital TV set top box
And also see the lowdown on Freeview, and whether you should care
If you're new to Digital TV, or have yet to make the leap, start by reading Prepare yourself for Digital TV