什么是網(wǎng)絡(luò)瀏覽器

　　學(xué)習(xí)啦小編為大家介紹了網(wǎng)絡(luò)瀏覽器，希望對你有幫助哦!

　　Google Inc.'s move to offer its own Web browser begs a question about a technology that most people now take for granted: What exactly is a Web browser?

　　The short answer is that it is a piece of software that takes us where we want to go, whether to buy a pair of pants or call up a bus schedule. To understand what a browser really does, though, it helps to understand why it was invented.

　　Computers were once isolated calculation engines. A user walked up to them, inserted a stack of punch cards or pushed some buttons, and waited for an answer. Later users could interact with a specific system using terminals sold by each computer maker, a phase followed by networks that could connect different kinds of computers run by individual organizations.

　　In the 1970s, researchers agreed on a set of specifications to send packets between those dissimilar systems -- akin to the address scheme the post office uses to route letters. Thus was born the Internet.

　　But viewing information on someone else's computer still wasn't easy. For one thing, the information might be stored in a database or other proprietary software that varied among organizations. Tim Berners-Lee, the man credited with inventing the Web, wanted to break down those barriers.

　　He built on a technology known as hypertext -- the notion of establishing links to connect any concept, or document, to any other. That required developing and popularizing three sets of rules for creating and exchanging documents.

　　One is hypertext transfer protocol, or HTTP, which establishes specifications for linking documents. Another is an address scheme for finding documents, known as a universal resource locator, or URL. Third is a way to create documents in a consistent format, known as hypertext markup language, or HTML.

　　But there was still one key element missing: a piece of desktop software to display documents created using HTML, and respond to the communications instructions based on HTTP and URL. So Mr. Berners-Lee created the first browser, a type of program that would later be refined by Netscape Communications Corp., Microsoft Corp. and others.

　　Today's browsers have been updated to do additional tricks. By using small programs, known as plug-ins, they can allow users to view videos and animations.

　　But browsers still must manage the more basic chores of displaying documents and navigating between them. When a user clicks on a link on a Web page -- or types a URL into the address line and hits return -- the browser sends a request for information that is converted into data packets and sent out to the Internet.

　　The request is routed through organizations that manage directories of domain names, and store numerical addresses associated with those names. Once that request reaches the server with that address, it responds by sending a new Web page that bounces back around the Internet to pop up on the user's browser.

　　谷歌(Google Inc.)計劃推出自主開發(fā)的網(wǎng)絡(luò)瀏覽器;但這并不意味著人人都了解這項(xiàng)大家都習(xí)以為常的技術(shù)。那么，究竟什么是網(wǎng)絡(luò)瀏覽器呢?

　　簡單的說，網(wǎng)絡(luò)瀏覽器就是一款軟件，能帶我們?nèi)ハ肴サ木W(wǎng)站，無論是去買條褲子還是查詢公交時刻表。不過，為了理解網(wǎng)絡(luò)瀏覽器的真正用途，我們有必要回顧下瀏覽器的誕生歷史。

　　最初，電腦是孤立的運(yùn)算機(jī)器。使用者打開機(jī)器，插入一張穿孔卡片或按下某些按鍵，然后等待機(jī)器給出一個答案。后來，使用者可以使用電腦制造商出售的終端，通過一個特殊系統(tǒng)與機(jī)器進(jìn)行互動;接下來出現(xiàn)了電腦網(wǎng)絡(luò)，它能夠?qū)⒏鲉为?dú)組織運(yùn)行的各種電腦連接起來。

　　在20世紀(jì)70年代，研究人員確定了一系列標(biāo)準(zhǔn)，得以在不同系統(tǒng)之間發(fā)送信息包──這類似于郵局發(fā)送信件的地址系統(tǒng)。互聯(lián)網(wǎng)由此誕生了。

　　不過，瀏覽他人電腦上的信息仍非易事。首先，信息可能存儲在數(shù)據(jù)庫，或其他所有權(quán)軟件中，而各組織所采用的又各不相同。Web之父蒂姆•伯納斯•李(Tim Berners-Lee)當(dāng)時希望能夠打破這些障礙。

　　他利用一種稱為超文本的技術(shù)，提出了在任何概念和文件之間建立連接的想法。由此發(fā)展并推廣了三套技術(shù)標(biāo)準(zhǔn)，用于創(chuàng)建與交換文件。

　　其中之一就是超文本傳輸協(xié)議，即HTTP，為文件連接確定了標(biāo)準(zhǔn)。另一套標(biāo)準(zhǔn)是統(tǒng)一資源定位符，即URL，用于尋找文件的地址系統(tǒng)。第三套標(biāo)準(zhǔn)是超文本置標(biāo)語言，即HTML，以一致的格式創(chuàng)建文件。

　　不過，我們還需要一個關(guān)鍵要素：一個可以顯示以HTML標(biāo)準(zhǔn)創(chuàng)建的文件、并可以響應(yīng)基于HTTP與URL標(biāo)準(zhǔn)通信指令的電腦軟件。因此，伯納斯•李發(fā)明了第一個瀏覽器;在這個基礎(chǔ)上，Netscape Communications Corp.、微軟(Microsoft Corp.)以及其他公司后來紛紛研發(fā)了各自的瀏覽器軟件。

　　如今的瀏覽器已經(jīng)過升級，可以進(jìn)行更多的任務(wù)。通過使用俗稱插件的小程序，用戶可以通過瀏覽器觀看視頻和動畫。

　　不過瀏覽器仍然必須滿足最基本的顯示文件和瀏覽功能。當(dāng)用戶點(diǎn)擊網(wǎng)頁上的鏈接時，或是在地址欄輸入URL網(wǎng)址然后點(diǎn)擊回車，瀏覽器就會發(fā)送一條相應(yīng)的信息請求，這些信息已被轉(zhuǎn)化為數(shù)據(jù)包并發(fā)送到了互聯(lián)網(wǎng)上。

　　這一請求信息要途經(jīng)管理域名地址錄、并儲存這些域名相關(guān)地址的組織。一旦信息請求抵達(dá)目的服務(wù)器，服務(wù)器就會發(fā)送一個新的網(wǎng)頁，沿著互聯(lián)網(wǎng)回復(fù)到用戶的瀏覽器上。