BDT: UTC + 6
Summer DST: not observed.
Coordinated Universal Time (UTC) is a high-precision atomic time standard which approximately tracks Universal Time (UT). It is the basis for legal civil time all over the Earth: time zones around the world are expressed as positive and negative offsets from UTC. In this role it is also referred to as Zulu time (Z), or using the historical term "Greenwich Mean Time" (GMT).
Daylight saving time (DST), often referred to as daylight savings time, is a widely used system of adjusting the official local time forward, usually one hour, from its official standard time for the summer months.