Sometime, it is said that trademark is an adjective, not a noun or verb. Two symbol normally people seen when it refers to trademark but most of the people don't know when to use what symbol. So, understand the basic things about trademark usage correctly which are as follows:
First, understand that we can use symbol after filing the trademark application regardless of its registration or objections on trademark application. Using a symbol is like a notice to the competitor that a mark is your trademark. There is no requirement to submit any paper or obtain any permission.
Similarly, for the registered trademark, you must use trademark symbol if you really want to sue your business competitors to claim damages. In case, you don't mention your trademark properly then you can not claim the damages. Don't use symbol until your trademark is finally registered. After registration, the trademark authority gives a trademark certificate.
Therefore, always keep in mind that, place your trademark on place prominently so that people can notice it immediately. Also if you are using your trademark within the body of text use some different style or fonts like bold, italics or UPPERCASE so that your trademark looks different from the surrounding words.
Wrong way: Nike athletic shoes
Correct way: Nike athletic shoes
The ? symbol means "service mark", which denotes services instead of goods. However, because the abbreviation SM has another, derogatory meaning that's why it is rarely used. Therefore, people use symbol which works identically, and, should be preferred.