What does “budget airlines” mean?

Native speaker’s answer
Rebecca
"Budget airlines," also known as low-cost or discount airlines, refers to an airline that is usually low-cost and offers less amenities (services) than a typical airline. For example, a budget airline might not offer food or drink service, or you might be charged for every item of baggage you bring onboard. Ex: Budget airlines are quite popular in Europe. Ex: I flew with a budget airline, so I couldn't bring much luggage with me.