Differencebetween Float:Left VS Display:Inline? While Every Element in Browser Goes to Left by Default

float:left; vs display:inline; vs display:inline-block; vs display:table-cell;

Of the options you asked about:

• float:left;
  
  I dislike floats because of the need to have additional markup to clear the float. As far as I'm concerned, the whole float concept was poorly designed in the CSS specs. Nothing we can do about that now though. But the important thing is it does work, and it works in all browsers (even IE6/7), so use it if you like it.

The additional markup for clearing may not be necessary if you use the :after selector to clear the floats, but this isn't an option if you want to support IE6 or IE7.

• display:inline;
  
  This shouldn't be used for layout, with the exception of IE6/7, where display:inline; zoom:1 is a fall-back hack for the broken support for inline-block.

• display:inline-block;
  
  This is my favourite option. It works well and consistently across all browsers, with a caveat for IE6/7, which support it for some elements. But see above for the hacky solution to work around this.

The other big caveat with inline-block is that because of the inline aspect, the white spaces between elements are treated the same as white spaces between words of text, so you can get gaps appearing between elements. There are work-arounds to this, but none of them are ideal. (the best is simply to not have any spaces between the elements)

• display:table-cell;
  
  Another one where you'll have problems with browser compatibility. Older IEs won't work with this at all. But even for other browsers, it's worth noting that table-cell is designed to be used in a context of being inside elements that are styled as table and table-row; using table-cell in isolation is not the intended way to do it, so you may experience different browsers treating it differently.

Other techniques you may have missed? Yes.

• Since you say this is for a multi-column layout, there is a CSS Columns feature that you might want to know about. However it isn't the most well supported feature (not supported by IE even in IE9, and a vendor prefix required by all other browsers), so you may not want to use it. But it is another option, and you did ask.

• There's also CSS FlexBox feature, which is intended to allow you to have text flowing from box to box. It's an exciting feature that will allow some complex layouts, but this is still very much in development -- see http://html5please.com/#flexbox

Hope that helps.

Why adding the property float left makes the div behave like an inline-block

Using float takes the elements out of the normal document flow in a way that other inline elements can wrap around them; it does not make them behave like inline-block elements.

If you would like alternative ways to achieve the same effect, give a look at the following examples.

Example 1:

Here's an example using display: flex on the parent element to make the children stay on the same line.

body {  display: flex;}
#block1 {  width: 20%;  background-color: red;  height: 100px;}
#block2 {  width: 70%;  background-color: yellow;  height: 100px;}

<div id="block1"></div><div id="block2"></div>

.alert{
  display: table;
}

.fa{
  display: table-cell;
  vertical-align:top;
}
p{
  display: table-cell;
  padding-left:5px;
}

<div id="foo" >Hello</div>
<br />
World!

#foo
{
    background-color:red;
    height:400px;
    display: inline-block;
}