The fighting between Israel and Hezbollah is what the U.S. military calls "asymmetrical". In other words, the opposing forces are so different that they'll never fight on the same terms. For a high-tech conventional land and air power like Israel, this means its airplanes, tanks and artillery work hard to find targets that will hold still -- and whose destruction will make a strategic difference. For Hezbollah, a lack of conventional forces means it relies on improvised terror weapons whose effects are difficult to predict.
Short-range ballistic missiles called Katyushas comprise the backbone of the Hezbollah arsenal. The terror group has fired around 1,000 at Israel cities including Haifa since the start of the current crisis. Ha'Aretz fills in the details:
Hezbollah's original Katyusha rockets had a range of 12 kilometers to 22 kilometers. At a later stage, it obtained Iranian Fajar-3 and Fajar-5 rockets, with a range of 45 kilometers and 75 kilometers, respectively. Hezbollah did not use these rockets until the current conflict.