In GNU Assembler, what does a dot signify at the beginning of a name?

The following is a line from a microprocessor startup file, intended for input into the GNU assembler as:

.section  .isr_vector,"a",%progbits

Does the dot at the beginning of the name .isr_vector mean anything special? PS: This name is referenced by the GNU linker ld.

EDIT:

This name also shows up in readelf output as a Section Header:

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  ...
  [ 1] .isr_vector       PROGBITS        08000000 008000 0001ac 00   A  0   0  1