diff --git a/bootloaders/zero/readme.txt b/bootloaders/zero/readme.txt
index 7835157f767d588eae92812d0bd86eef1a2069ba..688a4ad2ad0b28bebd8ab4690d7fffa3165f005f 100644
--- a/bootloaders/zero/readme.txt
+++ b/bootloaders/zero/readme.txt
@@ -11,4 +11,9 @@ SAM_BA_BOTH_INTERFACES for enabling both the interfaces
 
 SAM_BA_INTERFACE value should be modified in
 Project Options -> C/C++ Compiler -> Preprocessor -> Defined symbols
-Project Options -> Assembler -> Preprocessor -> Defined symbols
\ No newline at end of file
+Project Options -> Assembler -> Preprocessor -> Defined symbols
+
+3- Start application check
+
+Bootloader checks for the state of BOOT_LOAD_PIN (configurable by the user from main.h). If BOOT_LOAD_PIN is pulled low, bootloader execution is resumed.
+Else, the first location of application is fetched and checked. If it is empty (0xFFFFFFFF), then bootloader execution is resumed. Else it jumps to application and starts execution from there.