Choosing a pair of binoculars to be used for serious birding is not an easy task. There are a number of aspects to take into account starting with price.
It is fair to say that the more you spend the better the binoculars and the better they will be in the field. My advice is that you should spend as much as you can afford but do not buy the cheapest on the market. They make look good on the outside, but it is the quality of what’s inside that really matters.
The next thing to consider is the pair of numbers shown on all binoculars. You may see 8X50, 10X42, 10X25 and other combinations. What do these numbers mean? The first number (eg. 8 or 10) is the magnification. Essentially it means how big the object will be when looking through the binoculars. So, a bird viewed with an 8X magnification will be smaller than one viewed with a 10X magnification. This doesn’t mean that the 10X is better than the 8X. If you are doing general birding an 8X pair is probably good enough. If you someone who like to scan 1,000 waders looking for rarities, then the 10X is more suitable.
The second number on your 8X50 or 10X42 pair of binoculars represents the diameter of the front aperture. The higher the number the more light enters the binoculars, and the brighter the image when looking through them.
There is another important consideration when choosing a pair of binoculars and that is the weight of them. If you are carrying binoculars on long walks or hikes, then weight matters. I think it is also fair to say that some female or older birdwatchers would be happier to take a lighter pair. So you would expect a pair of 10X50 binoculars to weigh significantly more than a 8X25 pair.
Lastly, you should consider the closest distance that they can focus. This may sound very odd as you tend to think that birdwatching is about seeing birds in the distance. In some habitats, such as forest, you may want to focus on a bird that is 2 or 3 metres away from you. Seeing that forests are generally gloomy you would probably need a pair that lets in more light.
Your choice of binoculars is up to you but bear the above points in mind. For most of my birdwatching “career” I have used a pair of 10X42 binoculars that were the top of the range many years ago. They are still my favourite pair of binoculars and are worth what I paid for them.