Align a Div to Center

How to align a <div> to the middle (horizontally/width) of the page

<body>
    <div style="width:800px; margin:0 auto;">
        centered content
    </div>
</body>

How can I center a div within another div?

You need to set the width of the container (auto won't work):

#container {
    width: 640px; /* Can be in percentage also. */
    height: auto;
    margin: 0 auto;
    padding: 10px;
    position: relative;
}

The CSS reference by MDN explains it all.

Check out these links:

auto - CSS reference | MDN
margin - CSS reference | MDN
What is the meaning of auto value in a CSS property - Stack Overflow

In action at jsFiddle.

How to align <div> to center?

margin auto do not work until you do not give the width of that element.

 <div style="margin:0px auto; display:block; width:500px;">

            <asp:Menu ID="Menu1" runat="server" Orientation="Horizontal">
                <Items>
                    <asp:MenuItem Text="Home" NavigateUrl="Home.aspx" />
                    <asp:MenuItem Text="test" NavigateUrl="test.aspx" />
                    <asp:MenuItem Text="Reports" NavigateUrl="Reports.aspx" />
                    <asp:MenuItem Text="Review" NavigateUrl="Review.aspx" />
                    <asp:MenuItem Text="Management" NavigateUrl="mg.aspx" />
                    <asp:MenuItem Text="Scripts" NavigateUrl="scr.aspx" />
                    <asp:MenuItem Text="Notification" NavigateUrl="Notification.aspx" />
                </Items>
            </asp:Menu>
</div>

How to align 3 divs (left/center/right) inside another div?

With that CSS, put your divs like so (floats first):

<div id="container">
  <div id="left"></div>
  <div id="right"></div>
  <div id="center"></div>
</div>

P.S. You could also float right, then left, then center. The important thing is that the floats come before the "main" center section.

P.P.S. You often want last inside #container this snippet: <div style="clear:both;"></div> which will extend #container vertically to contain both side floats instead of taking its height only from #center and possibly allowing the sides to protrude out the bottom.

<div align=center></div> is this bad?

You could have a class of center in your CSS which works for most block elements.

For the CSS code:

.center {margin:0 auto;}

In your HTML:

<div class="center">Content Here</div>

If you wanted the text to be aligned center aswell as the div then you would just update the above CSS to be:

.center {margin:0 auto; text-align:center;}