From Wikipedia:
Git is a version control system that is used for software development and other version control tasks. As a distributed revision control system
it is aimed at speed, data integrity, and support for distributed, non-linear workflows.
Git was created by Linus Torvalds in 2005 for development of the Linux kernel, with other kernel developers contributing to its initial development.Its current maintainer is Junio Hamano.
As with most other distributed version control systems, and unlike most client–server systems, every Git directory on every computer is a full-fledged repository with complete history and full version-tracking capabilities, independent of network access
or a central server.
Like the Linux kernel, Git is free software distributed under the terms of the GNU General Public License version 2.
Git是一個用於軟件開發和其他版本控制任務的版本控制系統。作爲一個分佈式修訂控制系統，它的目的是速度，數據完整性以及支持分佈式和非線性工作流。
Git是2005年由Linus Torvalds在2005年爲Linux內核開發而開發的，其他的開發對它最初的發展也做出了貢獻。它目前的維護者是Junio Hamano.
不像其他大多數的客戶服務器系統和分佈式版本控制系統，在每一臺計算機的每一個在Git目錄是一個獨立於網絡連接或中心服務器的，帶有完整歷史和詳盡的版本追蹤能力的成熟的倉庫。
類似於Linux內核，Git是一個在遵循GNU通用公告許可協議條款的version2免費軟件。
Torvalds quipped about the name git (which means "unpleasant person"
in British English slang): "I'm an egotistical bastard, and I name all my projects after myself. First 'Linux', now 'git'." The man page describes Git as "the stupid content tracker". The readme file of the source code elaborates further:
Torvalds打趣說這個名字“git”（它的意思在英語俚語中是無用的人）：我是一個自我的怪物，我給我的工程取名字開始是“Linux”，現在是“git”。手冊裏描述“Git”爲“愚蠢的內容追蹤器”。源碼的自述文件中更進一步的說明了：
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker"
and the name as (depending on your mood):
當他剛好寫第一個版本的時候，便去了“git”這個名字。他描述這個工具爲“愚蠢的追蹤器”和這個名字（取決於你的心情）：
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
——隨機的 。 三個字組合是可發音而且沒有被用做任何Unix命令。跟“Get”的錯誤發音有或者沒有關係。
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
——愚蠢的。 卑鄙的，簡單的。從俚語詞典選出來的。
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks
——“全面的信息追蹤器”：如果你是好心情，它實際上對你很有幫助。天使在唱歌，一米陽光突然投射進房間。
——當它中斷的時候他就是該死的一車翔。
總結：大致可以理解爲Git就是一個可以處理或大或小的項目版本管理軟件。GitHub 是一個面向開源及私有軟件項目的託管平臺，也就是說提供Git服務的平臺。