在本地，我刚刚运行docker pull wordpress：
$docker pull wordpress
Using default tag: latest
latest: Pulling from library/wordpress
7268d8f794c4: Already exists
a3ed95caeb02: Download complete
38331772e700: Pull complete
74507bbf90f9: Downloading [=========> ] 13.47 MB/69.26 MB
c6734ca38ed8: Download complete
616f76e75b9d: Download complete
763f79680cbb: Download complete
e70b2d142af2: Download complete
62012af41161: Download complete
33a120b6dfa1: Download complete
ea474957253d: Download complete
757eabb832b4: Downloading [=============> ] 8.518 MB/31.61 MB
286426d94368: Download complete
cde52c0a5f98: Download complete
7c925ca09be1: Download complete
7c4e1930593c: Downloading [============> ] 1.127 MB/4.443 MB
9c4eeb87aed8: Waiting
e13c8ae5c7d1: Waiting
730edfa5d07f: Waiting
Using default tag: latest不言自明。但是，我不清楚所有这些哈希值，例如c6734ca38ed8和a3ed95caeb02代表。
你能解释一下吗？