Final answer:
A CSS transition allows an element to gradually change styles, such as on hover, and is specified using the 'transition' property, which includes the CSS property to change, the duration, timing function, and delay.
Step-by-step explanation:
The type of CSS effect that allows an element to gradually change from one style to another is known as a CSS transition. To create a CSS transition, you can use the transition property in your stylesheet. This property requires you to specify the CSS property you want to add an effect to, the duration of the effect, the timing function, and, if needed, a delay before the effect begins. For example:
{
element {
transition: background-color 0.5s ease-in;
}
element:hover {
background-color: #3498db;
}
}
In this example, when you hover over the element, the background color will change to #3498db over 0.5 seconds, using the ease-in timing function for a smooth start to the transition.