The verb tocar (conjugation) means "to touch" or "to play an instrument)". It has an orthographic change from c to qu in the preterite and the present subjunctive. See the conjugation in the present tense below:

Yo toco las flores.

I touch the flowers.

Alguien toca a la puerta.

Someone knocks on the door.

Él toca la guitarra todos los días.

He plays the guitar every day.

Se mira pero no se toca.

You can watch but you can't touch.

Note: tocar is also commonly used in a pronominal/reflexive form with the pronouns me, te, le, nos, os, les, as in the following examples:

to have a turn

Te toca recoger la mesa.

It's your turn to clean the table.

to correspond to

Me toca la mitad.

I get half.