Development of new specifications of language of a marking of the hypertext takes considerable term, and for this time the companies making browsers, have time to release some versions of the products. Therefore in section of heading one more tag <META> allowing authors of the document to define the information, not having the relation to HTML can be added.

A browser for actions, which are not stipulated by current specification HTML, uses this information. The tag <META> is not required probably to you for creation of the first HTML-documents, but it for certain is required to you, when your pages become more complex.

Example

<META HTTP-EQUIV = "refresh" CONTENT = "60" RL =" http://www.my_host.com/index.html ">

Browsers Netscape Navigator and Internet Explorer will understand this record as the instruction to expect 60 seconds, and then to load the new document. Such instruction is frequently used at change of a site of documents. The small document with the resulted line can be left on an old site of the document for the automatic reference to his(its) new site.

The next line:

<META HTTP-EQUIV = "refresh" CONTENT ="60">

instructs a browser to reload page each 60 seconds. It can be useful, if the data on page are frequently updated, for example, in case of tracking stock market prices.

There was rather popular an application of an element <META> for the decision of some typical tasks. As an example it is possible to result the indication of the keywords used by search engines. This way allows including additional words, which can obviously not enter into its content in an index of the document. For this purpose in a tag <META> as value of parameter NAME is underlined a name of some property. And by means of parameter CONTENT value of the given property, for example is underlined:

<META NAME = "author" CONTENT ="Metamorphosis Design Studio">

Specification HTML does not determine any concrete names of the properties, which are written down in a tag <META>. However there are some frequently used properties, for example, description, keywords, author, robots, etc.:

<META NAME = "description" CONTENT = " the Description of opportunities of language HTML 4.0">

<META NAME = "keywords" CONTENT = " a tag, the hypertext, HTML, a browser ">

The tag <META> can have the parameters specified in tab. 1.2.

Table 1.2.Parameters of a tag <META>

Parameter	Purpose
HTTP-EQUIV	Defines property for a tag
NAME	Provides the additional description of a tag. If this parameter is omitted, it is considered equivalent to parameter HTTP-EQUIV
URL	Defines the address of the document for property
CONTENT	Defines returned value for property

One more important applicability of a tag <META> is an indication of the coding of the text.

Other elements of heading

At section of heading of the document there can be two more tags — <STYLE> and <SCRIPT>. Their purpose is connected to use of tables of styles in the document and record of scripts.