Semi-permanent hair color is a type of hair dye that fades gradually over time. Unlike permanent hair color, which penetrates the hair shaft and lasts until the hair grows out, semi-permanent hair color only coats the outer layer of the hair and typically lasts anywhere from 4-8 weeks depending on factors like hair porosity, the color of the dye, and how frequently the hair is washed.

Here are some features and benefits of semi-permanent hair color:

1. Temporary: Semi-permanent hair color is a great option if you want to experiment with a new hair color without committing to it long-term. It fades gradually over time, allowing you to switch up your look as often as you like.

2. Low Maintenance: Semi-permanent hair color requires less maintenance than permanent hair color. Because it only coats the outer layer of the hair, it doesn't require the same level of processing or aftercare that permanent hair color does.

3. Gentle: Semi-permanent hair color is generally gentler on the hair than permanent hair color. It doesn't contain harsh chemicals like ammonia or peroxide, which can damage the hair.

4. Add Shine: Semi-permanent hair color can add shine and vibrancy to the hair. It can enhance the natural color of your hair or provide a subtle change in color without making a drastic change.

5. Cover Gray Hair: Semi-permanent hair color can be used to cover gray hair. While it may not be as long-lasting as permanent hair color, it can provide a temporary solution for people who want to cover gray hair without committing to permanent color.

6. Customizable: Semi-permanent hair color can be customized by mixing different colors to create a unique shade that complements your skin tone and hair type.

7. Fade Out Gradually: Semi-permanent hair color fades out gradually over time, so there is no harsh line of demarcation as the hair grows out. This makes it a good choice for people who want a natural-looking hair color that blends in with their natural hair color.