Logotypes are logos that just use the name of a company, so no graphics, icons or mascots. Just the name. These types of logos are very popular at large brands that are well known. It’s also the ideal way to let customers know who you are when you are just starting out as a business.
Google is probably one of the best and most successful examples of the uses of a logotype as their logo is simple yet very recognisable without using icons or additional graphics.
A logotype works well with brands that provide many services and may have more than one business (like Google). While you could use the typical magnifying glass in Google’s logo, it wouldn't work well with all the other brands and services that Google currently provides.
Logotypes also shows a kind of professionalism because of its simplicity. These logos are some examples of this: