Baseline is where the bottom of a text character sits. Sidenote: Parts of a character that descends past the baseline (characters: y, p, q, j) are called descenders.
In graphic design, baselines are used to align content in different columns so that they line up with one another. For example, if you read a magazine article and see two columns side by side, they should share the same baselines.
This is especially useful when you have elements that make columns shift positioning. Let's say on one column you have some text and on the other, you have an image that pushes down the second column. How do you align the second column? Most people would just look at the padding between the image and the second column of text when in reality, it's probably best to also look at whether or not it's sharing the same baseline as the first column.
In graphic design, baselines are used to align content in different columns so that they line up with one another. For example, if you read a magazine article and see two columns side by side, they should share the same baselines.
This is especially useful when you have elements that make columns shift positioning. Let's say on one column you have some text and on the other, you have an image that pushes down the second column. How do you align the second column? Most people would just look at the padding between the image and the second column of text when in reality, it's probably best to also look at whether or not it's sharing the same baseline as the first column.