我使用css做了一个小示例

.hover {
  position: relative;
  top: 50px;
  left: 50px;
}

.tooltip {
  /* hide and position tooltip */
  top: -10px;
  background-color: black;
  color: white;
  border-radius: 5px;
  opacity: 0;
  position: absolute;
  -webkit-transition: opacity 0.5s;
  -moz-transition: opacity 0.5s;
  -ms-transition: opacity 0.5s;
  -o-transition: opacity 0.5s;
  transition: opacity 0.5s;
}

.hover:hover .tooltip {
  /* display tooltip on hover */
  opacity: 1;
}

<div class="hover">hover
  <div class="tooltip">asdadasd
  </div>
</div>

• • 小提琴**

http://jsfiddle.net/8gC3D/471/

使用title属性：

<a href="#" title="Tooltip here">Link</a>

类似于koningdavid的，但在显示器上工作：无和块，并增加了额外的样式。

div.tooltip {
  position: relative;
  /*  DO NOT include below two lines, as they were added so that the text that
        is hovered over is offset from top of page*/
  top: 10em;
  left: 10em;
  /* if want hover over icon instead of text based, uncomment below */
  /*    background-image: url("../images/info_tooltip.svg");
            /!* width and height of svg *!/
            width: 16px;
            height: 16px;*/
}


/* hide tooltip */

div.tooltip span {
  display: none;
}


/* show and style tooltip */

div.tooltip:hover span {
  /* show tooltip */
  display: block;
  /* position relative to container div.tooltip */
  position: absolute;
  bottom: 1em;
  /* prettify */
  padding: 0.5em;
  color: #000000;
  background: #ebf4fb;
  border: 0.1em solid #b7ddf2;
  /* round the corners */
  border-radius: 0.5em;
  /* prevent too wide tooltip */
  max-width: 10em;
}

<div class="tooltip">
  hover_over_me
  <span>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec quis purus dui. Sed at orci. </span>
</div>

这个很有趣
仅限HTML和CSS

.help-tip {
  position: absolute;
  top: 18px;
  left: 18px;
  text-align: center;
  background-color: #BCDBEA;
  border-radius: 50%;
  width: 24px;
  height: 24px;
  font-size: 14px;
  line-height: 26px;
  cursor: default;
}

.help-tip:before {
  content: '?';
  font-weight: bold;
  color: #fff;
}

.help-tip:hover span {
  display: block;
  transform-origin: 100% 0%;
  -webkit-animation: fadeIn 0.3s ease-in-out;
  animation: fadeIn 0.3s ease-in-out;
}

.help-tip span {
  display: none;
  text-align: left;
  background-color: #1E2021;
  padding: 5px;
  width: 200px;
  position: absolute;
  border-radius: 3px;
  box-shadow: 1px 1px 1px rgba(0, 0, 0, 0.2);
  left: -4px;
  color: #FFF;
  font-size: 13px;
  line-height: 1.4;
}

.help-tip span:before {
  position: absolute;
  content: '';
  width: 0;
  height: 0;
  border: 6px solid transparent;
  border-bottom-color: #1E2021;
  left: 10px;
  top: -12px;
}

.help-tip span:after {
  width: 100%;
  height: 40px;
  content: '';
  position: absolute;
  top: -40px;
  left: 0;
}

<span class="help-tip">
    	<span > This is the inline help tip! </span>
</span>

纯CSS：

.app-tooltip {
  position: relative;
}

.app-tooltip:before {
  content: attr(data-title);
  background-color: rgba(97, 97, 97, 0.9);
  color: #fff;
  font-size: 12px;
  padding: 10px;
  position: absolute;
  bottom: -50px;
  opacity: 0;
  transition: all 0.4s ease;
  font-weight: 500;
  z-index: 2;
}

.app-tooltip:after {
  content: '';
  position: absolute;
  opacity: 0;
  left: 5px;
  bottom: -16px;
  border-style: solid;
  border-width: 0 10px 10px 10px;
  border-color: transparent transparent rgba(97, 97, 97, 0.9) transparent;
  transition: all 0.4s ease;
}

.app-tooltip:hover:after,
.app-tooltip:hover:before {
  opacity: 1;
}

<div href="#" class="app-tooltip" data-title="Your message here"> Test here</div>

另一种类似的CSS实现方法：

#img {  }
#img:hover {visibility:hidden}
#thistext {font-size:22px;color:white }
#thistext:hover {color:black;}
#hoverme {width:50px;height:50px;}

#hoverme:hover { 
background-color:green;
position:absolute ;
left:300px;
top:100px;
width:40%;
height:20%;
}

<p id="hoverme"><img id="img" src="http://a.deviantart.net/avatars/l/o/lol-cat.jpg"></img><span id="thistext">LOCATZ!!!!</span></p>

试试Js Fiddle
以下是一些有关过渡和其他过渡方法的链接：

• http://www.w3schools.com/css3/css3_transitions.asp
• http://dev.opera.com/articles/view/css3-show-and-hide/

您可以使用title属性，例如，如果您想在文本上显示工具提示，只需：

<span title="This is a Tooltip">This is a text</span>

这是我的解决方案：
https://gist.github.com/BryanMoslo/808f7acb1dafcd049a1aebbeef8c2755
该元素包含一个“tooltip-title”属性和工具提示文本，并且在悬停时使用CSS显示，我更喜欢这个解决方案，因为我不必将工具提示文本作为HTML元素包含在内！

#HTML
<button class="tooltip" tooltip-title="Save">Hover over me</button>

#CSS

body{
    padding: 50px;
}
.tooltip {
    position: relative;
}

.tooltip:before {
    content: attr(tooltip-title);
    min-width: 54px;
    background-color: #999999;
    color: #fff;
    font-size: 12px;
    border-radius: 4px;
    padding: 9px 0;
    position: absolute;
    top: -42px;
    left: 50%;
    margin-left: -27px;
    visibility: hidden;
    opacity: 0;
    transition: opacity 0.3s;
}

.tooltip:after {
    content: "";
    position: absolute;
    top: -9px;
    left: 50%;
    margin-left: -5px;
    border-width: 5px;
    border-style: solid;
    border-color: #999999 transparent transparent;
    visibility: hidden;
    opacity: 0;
    transition: opacity 0.3s;
}

.tooltip:hover:before,
.tooltip:hover:after{
    visibility: visible;
    opacity: 1;
}