てみる is used when you want to say that you do something as an experiment or test, often to see what happens or how it feels. It's like 'try doing' in English. You use it when you haven't done it before or are unsure about the outcome. For instance, you might try a new food, try asking someone for help, or try using a new app. The main verb is in て-form, and みる works as a helper verb that carries the meaning of 'to try'. In casual speech, てみる often becomes てみる (same) but in writing or polite speech, it's てみます. Note that てみる cannot be used for actions you do regularly or habitually; it's for specific attempts.