语言是人类生活中不可或缺的部分，是人类重要的交际工具，也是人类和动物分道扬镳的最后标志。古代中国、古印度和古希腊等国家的人们很早就开始关注语言问题。对语言进行系统和科学研究的语言学（Linguistics）同样经历了漫长的发展过程——从最初的语文学（Philology）到历史比较语言学（Historical Comparative Linguistics）。而语言学家的语言观也在不断地发展——从语言工具论到语言非工具论。
　　20世纪初，索绪尔（F.Saussure）开创了现代语言学，揭开了人类语言研究的新篇章。他的结构主义思想影响了当时的很多学科，最终成为20世纪上半叶的时代精神。而且他的区分：能指与所指、历时与共时、语言与言语等至今仍是语言研究中的重要概念。
　　20世纪中叶，乔姆斯基（N.Chomsky）提出转换生成语法，掀起了语言研究的另一场革命，并对计算语言学等学科的发展提供了理论根基。20世纪80年代，我国也出现了研究转换生成语法的热潮。与此同时，韩礼德（M.A.K.Halliday）提出系统功能语法。这位与中国有着不解渊源的语言学家十分重视语言的社会性特征，因此他的理论对社会语言学、话语分析和文体学等都有很强的指导意义。
　　随着语言研究的深入，语言学必将迎来更加辉煌的明天。

　　《应用语言学方法导论》：
　　Other sciences work with objects that are given in advance and that can thenbe considered from different viewpoints； but not linguistics. Someone pronouncesthe French word nu "bare" ： a superficial observer would be tempted to call theword a concrete linguistic object； but a more careful examination would revealsuccessively three or four quite different things， depending on whether the word isconsidered as a sound， as the expression of an idea， as the equivalent of Latinnudum， etc. Far from it being the object that antedates the viewpoint， it wouldseem that it is the viewpoint that creates the object； besides， nothing tells us inadvance that one way of considering the fact in question takes precedence over theothers or is in any way superior to them.
　　Moreover， regardless of the viewpoint that we adopt， the linguisticphenomenon always has two related sides， each deriving its values from the other. For example：
　　1） Articulated syllables are acousticalimpressions perceived by the ear， but the sounds would not exist without the vocal organs； an n， for example， exists
　　only by virtue of the relation between the two sides. We simply cannot reduce language to sound or detach sound from oral articulation； reciprocally， we cannot define the movements of the vocal organs without taking into account the acoustical impression.
　　2） But suppose that sound were a simple thing： would it constitute speech?
　　No， it is only the instrument of thought； by itself， it has no existence. At this point a new and redoubtable relationship arises： a sound， a complex acoustical-vocal unit， combines in turn with an idea to form a complex physiological-psychological unit. But that is still not the complete picture.
　　3） Speech has both an individual and a social side， and we cannot conceive of one without the other.
　　4） Speech always implies both an established system and an evolution； at every moment it is an existing institution and a product of the past. To distinguish between the system and its history， between what it is and what it was， seems very simple at first glance ； actually the two things are so closely related that we can scarcely keep them apart. Would we simplify the question by studying the linguistic phenomenon in its earliest stages-if we began， for example， by studying the speech of children? No， for in dealing with speech， it is completely misleading to assume that the problem of early characteristics differs from the problem of permanent characteristics. We are left inside the vicious circle.
　　From whatever direction we approach the question， nowhere do we find the integral object oflinguistics. Everywhere we are confronted with a dilemma： if we fix our attention on only one side of each problem， we run the risk of failing to perceive the dualities pointed out above； on the other hand， if we study speech from several viewpoints simultaneously， the object of linguistics appears to us as a corifused mass of heterogeneous and unrelated things. Either procedure opens the door to several sciences-psychology， anthropology， normative grammar，philology， etc.-which are distinct from linguistics， but which might claim speech， in view of the faulty method of linguistics， as one of their objects.
　　As I see it there is only one solution to all the foregoing difficulties： from the very outset we must put both feet on the ground of language and use language as the norm of all other manifestations of speech. Actually， among so many dualities， language alone seems to lend itself to independent definition and provide a fulcrum that satisfies the mind.
　　……

第一章 语言与语言学
第二章 应用语言学
第三章 语用学
第四章 社会语言学
第五章 第二语言习得
第六章 外语教学
第七章 语言测试
第八章 话语分析
第九章 体裁分析
第十章 特殊目的英语
第十一章 跨文化交际