When your landlord wants to make deductions from your deposit at the end of your tenancy, the specific issues they point to are often described as "dilapidations". This can include things like holes in walls, broken fixtures, stained carpets, or damaged appliances, provided the deterioration goes beyond what would be expected from normal everyday use.
The key distinction is between dilapidations and fair wear and tear. Fair wear and tear is the landlord's responsibility, whereas dilapidations are the tenant's responsibility, but only to the extent that the damage exceeds normal use and only subject to apportionment for the age and condition of the item at the start of the tenancy.
In a deposit dispute, the landlord must prove that specific dilapidations exist, that they were caused during your tenancy (not pre-existing), and that the cost claimed is reasonable and doesn't constitute betterment. Your move-in and move-out documentation is the evidence that determines whether the landlord's claims hold up.