Learn Hardcore Italian: Io uso il libro sul tavolo.

In Italian, the simple present tense (uso) can be used to express both a habitual action and a current action. Unlike English, where you often use "I am using," Italian can simply say uso. If you want to emphasize that it is happening right now, you might use sto usando, but io uso is perfectly acceptable for everyday conversation.

Why do we say "il libro" and not "lo libro"?

Italian uses il before most masculine nouns starting with a consonant. Lo is used only before specific consonants like "z," "s+consonant," "gn," or "ps" (for example, lo zio, lo studente). Since libro starts with "l" followed by a vowel, il is the correct article.

What does "sul" mean, and why not just use "su"?

Sul is a contraction of su + il (preposition + article) and literally means on the in English. You could say su il tavolo, but it's grammatically correct (and typical) to contract them into sul tavolo.

Do I always need to say "Io uso", or can I just say "Uso il libro"?

Italian often drops the subject pronoun because the verb form indicates the person. Saying Uso il libro sul tavolo is perfectly natural, and in many contexts, more common than Io uso il libro sul tavolo. The inclusion of io just puts emphasis on the speaker.