Like PCR, but does not require thermal cycling. Thus the "isothermal" in the name: iso means same, so "same temperature".
Not needing the thermo cycling means that the equipment needed is much smaller and cheaper it seems.
Video 1.
Loop Mediated Isothermal Amplification (LAMP) Tutorial by New England Biolabs (2015)
. Source. Explains the basic LAMP concept well.

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