Q:

On my HTML website, why does changing my text-alignment within a paragraph tag automatically close the paragraph tag once rendered in a browser? 

This is a very small HTML question that I am sure you guys will answer quickly.   I post things on my website like this
<div id="content">
     <p>
          <hh>Header text here</hh>
          Post information here, text and stuff. 
     </p>

     <p>
          <hh>Header 2 text here</hh>
          Post 2 information here, text and stuff. 
     </p>
</div>

but when I try to insert a <center> or alight left tag, the <p> closes automatically, and everything after the <center> tag is outside the paragraph box.   I used inspect-element in firefox, and I can see it closes with a </p> that I never typed, right before any calls to centered text. 
For example: 
<p>
     <hh>Header 2 text here</hh>
     Post 2 information here, text and stuff. 
     <center>This text is centered</center>
</p>

is rendering as this:
<p>
     <hh>Header 2 text here</hh>
     Post 2 information here, text and stuff. 
</p>
<center>This text is centered</center>
</p>

This is really frustrating, and if someone could help me out that would be amazing.   using <div align-right> also doesn't work.   If it helps, I can set the entire <p> to align any way and it works. 
It ONLY breaks when I differ from the set orientation within that tag. 

A:

From w3school : 

Use CSS to center text! 
The  tag is not supported in HTML5.  Use CSS instead. 
The  element is deprecated in HTML 4.01. 

http://www.w3schools.com/tags/tag_center.asp
It is because center acts like a p. And you cannot put a p in a p.
EDIT : To answer to your comment, you should probably do this :
<p>
     <hh>Header 2 text here</hh>
     Post 2 information here, text and stuff. 
     <span>This text is centered</span>
<p>

And in your css add this
#content p span { display:block; text-align:center; }

(It also works with an a tag if you want it)

