List:

• HEAD @, eg. git checkout @ = git checkout HEAD
• upstream branch REF@{u} or REF@{upstream}, eg @{u} is current branch upstream
• parent commit ^, eg C0-> C1 -> C2 <- HEAD, HEAD^ is C1, @^ is C1, @^^ is C0 (it accepts a number, but usually tile is prefered: @^1 is C1 , HEAD^^ is C0, HEAD^2 is C0)
• nth parent ~<n>, eg C0-> C1 -> C2 <- HEAD, @~2 is C0

Reflog:

• "the n-th prior value of that ref" REFERENCE@{N}: master@{1} is the commit pointed by master, on the previous change (eg. on branch master pointing to C1 - git commit create C2: master{0} is C2, master{1} is C1)

Ranges:

• ancestors: r1 means all r1 ancestors, including r1
• interval:
  • ^r1 r2 means all commits between r1 and r2, excluding r1, eg ] r1; r2 ]
  • r1..r2 is shorthand for ^r1 r2, eg ] r1; r2 ]
• non-intersection: r1...r2: all commits reachable from r1 or r2, but not both

   G   H   I   J
    \ /     \ /
     D   E   F
      \  |  / \
       \ | /   |
        \|/    |
         B     C
          \   /
           \ /
            A

Args   Expanded arguments    Selected commits
D                            G H D
D F                          G H I J D F
^G D                         H D
^D B                         E I J F B
^D B C                       E I J F B C
C                            I J F C
B..C   = ^B C                C
B...C  = B ^F C              G H D E B C

Using symbols

B^-    = B^..B
       = ^B^1 B              E I J F B
C^@    = C^1
       = F                   I J F
B^@    = B^1 B^2 B^3
       = D E F               D G H E F I J
C^!    = C ^C^@
       = C ^C^1
       = C ^F                C
B^!    = B ^B^@
       = B ^B^1 ^B^2 ^B^3
       = B ^D ^E ^F          B
F^! D  = F ^I ^J D           G H D F

More with git help revisions

Get nearest ancestor not on branch (aka parent) with this gist

All these are equivalent

origin/master
remotes/origin/master
refs/remotes/origin/master

See API