In SQL Server, concurrent writes or read / write to the same page can lead to PAGELATCH (like PAGELATCH_EX and PAGELATCH_SH) waits or what is knowns as PAGELATCH contention.
One common use case is when invoice numbers are stored in a table. If the row is narrow, then many rows can fit in the 8KB page. This can lead to many invoicing number sequences being stored on the same page. When different invoicing number sequences are accessed from concurrent sessions, this can lead to PAGELATCH waits.
The way to solve this is to widen the rows so each row takes about a page and we don't have contention on the same page.
The below video demonstrates this with hands-on example. SQLTest Tool simulates the hands-on labs for you, no registration necessary. You can practice the online hands-on example while watching the Video.