Codenames, Tags, and Build Numbers

At a high level, Android development happens around families of releases, which use code names ordered alphabetically after tasty treats.

The code names match the following version numbers, along with API levels and NDK releases provided for convenience:

Code nameVersionAPI level
(no code name)1.0API level 1
(no code name)1.1API level 2
Cupcake1.5API level 3, NDK 1
Donut1.6API level 4, NDK 2
Eclair2.0API level 5
Eclair2.0.1API level 6
Eclair2.1API level 7, NDK 3
Froyo2.2.xAPI level 8, NDK 4
Gingerbread2.3.xAPI level 9, NDK 5

Starting with Cupcake, individual builds are identified with a short build code, e.g. FRF85B. The first letter is the code name of the release family, e.g. F is Froyo. The second letter is a branch code that allows Google to identify the exact code branch that the build was made from, and R is by convention the primary release branch. The next letter and two digits are a date code. The letter counts quarters, with A being Q1 2009. Therefore, F is Q2 2010. The two digits count days within the quarter, so F85 is June 24 2010. Finally, the last letter identifies individual versions related to the same date code, sequentially starting with A; A is actually implicit and usually omitted for brevity. The date code is not guaranteed to be the exact date at which a build was made, and it is common that minor variations added to an existing build re-use the same date code as that existing build.

Starting with Donut, the exact list of tags and builds is in the following table:

BuildTagNotes
DRC83android-1.6_r1.1 earliest Donut version, ADP1, ADP2
DRC92android-1.6_r1.2
DRD08android-1.6_r1.3
DRD20android-1.6_r1.4
DMD64android-1.6_r1.5latest Donut version
ESD20android-2.0_r1earliest Eclair version
ESD56android-2.0.1_r1
ERD79android-2.1_r1Nexus One
ERE27android-2.1_r2Nexus One
EPE54Bandroid-2.1_r2.1pNexus One
ESE81android-2.1_r2.1s
EPF21Bandroid-2.1_r2.1p2latest Eclair version
FRF85Bandroid-2.2_r1earliest Froyo version, Nexus One
FRF91android-2.2_r1.1Nexus One
FRG01Bandroid-2.2_r1.2
FRG22Dandroid-2.2_r1.3
FRG83android-2.2.1_r1Nexus One
FRG83Dandroid-2.2.1_r2Nexus One
FRG83Gandroid-2.2.2_r1latest Froyo version, Nexus One
GRH55android-2.3_r1earliest Gingerbread version, Nexus S
GRH78android-2.3.1_r1Nexus S
GRH78Candroid-2.3.2_r1latest Gingerbread version, Nexus S

The branches donut, eclair, froyo, gingerbread represent development branches that do not exactly match configurations that were tested by Google. They might contain a variety of changes in addition to the official tagged releases, and those haven't been as thoroughly tested.