UX research is all about understanding the needs, preferences, and behaviors of the people who will be using a product or service. There are lots of different ways to do this research, and the best method will depend on the project. Here are some of the most common methods:
User interviews: This is when you talk directly to users to gather information about their experiences and needs. You can do these interviews in person or remotely, and you can structure them (follow a set of predetermined questions) or make them more casual. User interviews are great for getting in-depth, qualitative data about user attitudes and behaviors.
Usability testing: This is when you watch people use a product or service to see if there are any problems or roadblocks. You can do this in a lab or in the real world, and you can test with just a few people or a larger group. Usability testing is a good way to identify specific issues with a product or service and figure out how to fix them. Tools like Useberry and UserTesting make it possible to recruit and facilitate testing from remote locations.
Eye tracking: This is when you use special software or hardware to track the movement of users' eyes as they use a product or service. This can help designers understand what parts of a product or service users are paying attention to and how they're interacting with it. Tools like VisualEyes, Tobii, and Eyegaze can be used for eye tracking.

A/B testing: This is when you show two different versions of a product or service to users and compare the results. This is a good way to see which design works better. Tools like Crazy Egg and Optimizely can help you set up and analyze A/B tests.

Card sorting: This is a technique for understanding how users organize and categorize information. You give users a set of cards with different pieces of information on them and ask them to group the cards in a way that makes sense to them. This can help designers understand how users think about and navigate through information, and it can be used to improve navigation and information architecture.
Ethnographic research: This is when you study users in their natural environment, often over a longer period of time. This can involve observations, interviews, and other methods, and it's a great way to understand user behavior and context in a more complete way. Ethnographic research can help identify unmet needs or opportunities for innovation.