The easiest way to label clothing is with a permanent laundry marker . The indelible ink lasts through many washings and is quick to use. The downside is that it can bleed through to the outside of a garment. And, once it does, it's permanent. You may also have some unhappy hand-me-down recipients if their sister's name is in the shirt.
There are now self-inking stamps that can be used to mark clothing. Again, they are quick and easy to use and have the same limitations as laundry marker.
Plenty of Web site sell customized iron-on or even peel and stick labels. These are convenient, not too expensive and will usually last through the life of the garment. And, if the garment is handed down a new label can be ironed over the last one.
You can make your own iron-on labels using twill tape, a laundry marker and some fusible web (available at any craft store). This is particularly helpful to know if your child springs the need for labels on you at the last minute.
There are beautiful custom woven labels that can be ordered to enhance your garments. They can be designed to showcase the seamstress or knitter who made the garment or with your name or monogram. These are lovely but sewing them in is time-consuming and they are the most expensive type of label. You must allow several weeks to place and receive your order.
One of the newest ways to label clothes is with a plastic tag that can be attached to a seam, hem or care label. The tag does not fade, is resistant to high temperatures and can be removed. You must order in advance and use a custom device to attach and remove the tags.
Specific questions? Just ask here.