Kitchen cabinets are just big boxes on your wall, which is great for storing dishes and drinking glasses, but bad for casting shadows on your counters. Make cooking so much better, more enjoyable, and just plain visible, by adding lighting to this one key spot. If you don't want to hardwire anything new, or rent your current home, here are some great inexpensive, easy-to-install options.
Puck lights (named for their hockey puck shape and size) use either xenon, halogen, or LED light bulbs. They are easy to install, and give single focused spots of light wherever they are placed. Depending on which type you buy, they either plug in to a wall outlet or require batteries, and either screw into the bottom of your cabinets, or can be stuck directly to any surface using provided adhesive dots. Know that battery-powered options are good for only occasional use, as battery life isn't terribly long (consider buying rechargeable batteries if you go this route). Some of these lights require you to "tap" them to turn on, but they also have remote control models that are dimmable.
Wireless LED Puck Light 6 Pack With Remote Control from Amazon; $34.99 with Prime Shipping
Fluorescent Light Bars
Unlike the big tubular ceiling lights you think of first when you hear the word fluorescent, these are fairly compact, can easily hide up under the cabinets without being seen, and are light enough to stay put using just velcro if you don't want to commit to screws. Most are plug-in models, but there are some that can be hardwired. Unlike the circular puck lights, the light on these is spread out across the bar, and covers more area. But because they are fluorescent, the light has that cool (and by cool I mean not warm) office-like quality that's not the most inviting. They also aren't dimmable. Depending on which you buy, some can be tethered together to turn on/off at the same time.
Extendable 22" Under Cabinet Light from Amazon; $34.10 for a Pack of Two with Prime Shipping
LED Light Bars
Like the other fixtures above, these are considered "plug and play" without messy rewiring. Most come with all the necessary hardware or adhesive patches, which makes installation a breeze. LED lights also have the added benefit of being very energy efficient. Unlike fluorescents, they are more adjustable, often with 3-way switches. Although they used to be more expensive, they've been around long enough now that prices have come down considerably, making them a great option.
LED Under Counter Lighting Kit from Amazon; $24.99 for a Three Pack with Prime Shipping
These combine the efficiency of LED bulbs with the flexibility of rope, making them an intriguing choice for your kitchen. They can be cut to size, are peel and stick, and you can do some fun things, like change the color of the lights to red or blue. Depending on how you configure it, make sure the set you buy has everything needed: many of these kits are modular and you have to add in adapters, dimmers, including wifi capability and Alexa compatibility, if that's up your alley. Even though their design makes it easy to cover a good area, just know that these don't have the light output of the other options.