PrefacePiero NicoliniE-mail: nicolini@fias.uni-frankfurt.deFrankfurt Institute for Advandced Studies (FIAS), Frankfurt am Main, GermanyandInstitut für Theoretische Physik, Goethe-Universitat Frankfurt am Main, GermanyDouglas SingletonE-mail: dougs@mail.fresnostate.eduDepartment of Physics, California State University Fresno, CA, USAandInstitute of Experimental and Theoretical Physics Al-Farabi KazNU, Almaty, KazakhstanShingo TakeuchiE-mail: shingo.portable@gmail.comThe Institute for Fundamental Study, “The Tah Poe Academia Institute”, Naresuan University, Phitsanulok, ThailandMatthew J. LakeE-mail: matthewj@nu.ac.thThe Institute for Fundamental Study, “The Tah Poe Academia Institute”, Naresuan University, Phitsanulok, ThailandandThailand Center of Excellence in Physics, Ministry of Education, Bangkok, ThailandVladimir DzhunushalievE-mail: v.dzhunushaliev@gmail.comInstitute of Experimental and Theoretical Physics Al-Farabi KazNU, Almaty, KazakhstanIntroductionThe Institute for Fundamental Study (IF) hosted the 6th IF+YITP International Symposium on superstring theory, the quantum theory of fields, gravity, cosmology, and related topics, on August 3rd through 5th, 2016, on the campus of Naresuan University, Thailand. This version of the symposium was co-sponsored by the Yukawa Institute for Theoretical Physics (YITP). These symposia have two principle aims. First, to bring together researchers from Thailand and around the world to discuss new ideas in fundamental physics. Second, these meetings are to support the recently established Institute for Fundamental Study (The Tah Poe Academia Institute) centered in Naresuan University in Phitsanulok, Thailand. The 6th symposium was a great success in terms of these two goals. The meeting had eight invited speakers and over 60 participants from both inside and outside Thailand. A host of new models and theories were presented at this symposium which covered a wide range of theoretical topics from cosmology to quantum field theory to superstring theory. The list of invited speakers and their talk titles is Committees and List of Participants are available in this PDF.AcknowledgmentsThe meeting was co-sponsored by the Asia Pacific Center for Theoretical Physics (APCTP), Pohang, Korea, Naresuan University, Phitsanulok, Thailand and the Yukawa Institute for Theoretical Physics (YITP), Kyoto, Japan. IF thanks the APCTP for providing generous financial support for several of the workshop participants and the YITP for their financial and logistical support for the meeting.