1、 Text title （h1-h6）

<h1>LOGO</h1> 
<h2> Secondary column or title - Subheading H2</h2> 
<h3> Again, we need column or classified subtitles H3</h3> 
<h4> In the article, the classification subtitle H4</h4> 
<h5> Secondary title </h5>
<h6> Six level title </h6>

html The principle of using the title label ：

H1 It's best to use it only once in a web page , For example, to a web page LOGO Use .

2、 Paragraph text (p)

<p> Paragraph text content </p>
Identify a paragraph ( There is a gap between paragraphs )

3、 Space

&nbsp;
There is no definite value for the occupied position , This has something to do with the current font size .

4、 Line break (br)

<br />
The wrap is an empty tag ( Forced line wrap )

5、 In bold Bold has two marks

A、<b> Bold content </b>
B、<strong> Bold content </strong>

6、 tilt

<em></em> ,<i></i>

7、 Level

<hr /> Empty tag

8、 list (ul,ol,dl)

HTML There are three kinds of lists in the ： Unordered list , Ordered list , Custom list

* Unordered list
An unordered list consists of ：
<ul>(unordered list)
<li></li>
<li></li>
．．．．．．
</ul>

* Ordered list
An ordered list consists of ：
<ol>(ordered list)
<li></li>
<li></li>
．．．．．．
</ol>

* Custom list
<dl>(definition list)
<dt> Noun </dt>
<dd> explain </dd>
(definition description)
．．．．．．
</dl>

Knowledge expansion 2---- Properties of ordered lists

1)、type: Specifies the type of bullet for list items in a list
grammar ：<ol type="a"></ol>
1 An ordered list of numbers in order （ The default value is ）（1, 2, 3, 4）.
a An ordered list of letters , A lowercase letter （a, b, c, d）.
A An ordered list of letters , Capitalization （A,B,C,D)
i Rome digital , A lowercase letter （i, ii, iii, iv）.
I Rome digital , Capitalization （I, ii, iii, iv）.
2)、start Property specifies the starting point of the sequence table .
grammar ：<ol start="5"></ol>

9、 Insert a picture

<img src=" Target file path and full name " alt=" Pictures replace text " title=" Picture title " />
notes : The image to be inserted must be placed under the site
title The role of :  Show a tip when you hover over the image , When the mouse leaves, it's gone ,HTML The vast majority of tags support title attribute ,title Attribute is specially used for prompt information
alt The role of :alt Property is a prompt message displayed on the page when your picture cannot be loaded for some reason , It will output directly where the image was originally loaded .

* The relative path ：
1) When the current file and the target file are in the same directory , Write the target file name directly + Extension ;<img src=”q12.jpg”/>
2) When the current file and the folder of the target file are in the same directory , It is written as follows ：
Folder name / Full name of the target file + Extension ;<img src=”images/q12.jpg”/>
3) When the folder of the current file and the folder of the target file are in the same directory , It is written as follows ：
../ The name of the folder where the target file is located / Target file name + Extension ;
<img src=”../images/q12.jpg”/>

10、 The application of hyperlinks

grammar ：
<a href=" Target file path and full name / Connection address " title=" Tip text "> Link text / picture </a>
<a href="#"></a> Empty link
attribute ：target: How the page opens , Default property value _self.
Property value ：_blank New window open
<a href="#" target="_blank"> The new page opens </a>

11、div and span Usage of

<div ></div>

No specific meaning , Collectively referred to as block labels ,
Used to set the document area , Is a common object for document layout

<span> </span>
Text node labels
It could be a small piece of text , Or a word .

12、 The function and composition of data table

effect ： Display the data

Table composition
<table width="value" height="value" border="value" bgcolor="value" cellspacing="value" cellpadding="value">
<tr>
<td></td>
<td></td>
</tr>
</table>

notes ： One tr For a line ; One td Means a column ( One cell )
* Related properties of data tables
1）width=" Width of table "
2）height=" Table height "
3）border=" The border of the table "
4）bgcolor=" The background color of the form " bg=background
5）bordercolor=" The border color of the table "
6）cellspacing=" Space between cells "
7）cellpadding=" The gap between cell and content "
8） Alignment mode ：align="left/center/right";
9) Merge cell properties ：
colspan=“ The number of columns in the cells you want to merge " Merge Columns ;

rowspan=“ Number of rows of cells to merge ” Merger line ;

13、 The function and composition of the form

What forms do ： Used to collect user information ;

1)、 Form box

<form name=" Form name " method="post/get" action=""></form>

2） The text box

<input type="text" value=" The default value is "/>

3) Password box

<input type="password" />
<input type="password" placeholder=" password " />

4) Reset button

<input type="reset" value=" Button content " />

5） Radio buttons / Radio button

<input type="radio" name="ral" />
<input type="radio" name="ral" checked="checked" />
In the radio button name Attribute must write , The same set of radio buttons name Property values must be the same .
checked="checked"( Selected by default ;) disabled="disabled" Ban

6） Check box

<input type="checkbox" name="like" />
<input type="checkbox" name="like" disabled="disabled" /> (disabled="disabled" : Ban )
(checked="checked" : Selected by default )

7) The drop-down menu

<select name="">
<option> Menu content </option>
</select>

8） Multi-line text box （ Text domain ）

<textarea name="textareal" cols=" Character width " rows=" Row number ">
</textarea>

9) Button

<input name="'" type="button" value=“ Button content ” />
<input name="'" type="submit" value=“ Button content ” />
<button></button>

button and submit Is the difference between the ：

submit The submit button is used to submit information ,type The type is button It's just a jump , Do not submit .

Expand your knowledge 3： For different input types ,value The meaning of attribute usage

value The attribute is input Element settings .
For different input types ,value Properties are used differently ：
type="button", "reset", "submit" - Define the text displayed on the button
type="text", "password" - Define the initial value of the input field
type="checkbox", "radio" - Define the value associated with the input
notes ：<input type="checkbox"> and <input type="radio"> Must be set in value attribute .

Expand your knowledge 4：

<form name=" Form name " method="post/get" action=""></form>

Form There are two ways to get data in get and post The difference between ？

1. get Get data from the server ,post Is to send data to the server .
2. get The parameter data queue is added to the submission form ACTION Attribute refers to URL in , Value corresponds to each field in the form one by one , stay URL Can be seen in .post It's through HTTP post Mechanism , Place the fields and their contents in the HTML HEADER Transfer to ACTION Attribute refers to URL Address . Users don't see the process .
3. about get The way , Server side Request.QueryString Get the value of the variable , about post The way , Server side Request.Form Get submitted data .
4. get Small amount of data transmitted , Not greater than 2KB.post Large amount of data transmitted , It is generally defaulted to unlimited .
5. get Very low security ,post High security . But it's more efficient than Post Good method .
Suggest ：
1、get The security of this method is better than Post The way is worse , If it contains confidential information , Suggest using Post Data submission method ;

2、 When you're doing a data query , Suggest using Get The way ; We're doing data additions 、 When modified or deleted , Suggest using Post The way ;