What is MTK?

MTK stands for MediaTek, and MediaTek is a well-known chip manufacturing company based in Taiwan that mostly outsources their products, hence they are regarded as Fabless companies. 

They specialize in manufacturing the Central Processing Unit (CPU chips) for wireless telecommunications, HDTVs, DVD etc. Their largest demands come from the Chinese mobile tech market. 

From that little description of MTK, you can deduce by now that when we say MTK phones, we are talking of phones that make use of MTK chips. Since MTK are largest suppliers of their chips to the Chinese mobile tech markets, it now tells us that most of the mobile devices produced in China are MTK devices.

What is a MediaTek processor?

MediaTek was originally a unit of United Microelectronics Corporation (UMC) tasked with designing chipsets for home entertainment products. On 28 May 1997, the unit was spun off and incorporated. MediaTek Inc. was listed on the Taiwan Stock Exchange (TSEC) under the "2454" code on 23 July 2001.