# TF Constants and Variables

Learn about TF constants and variables and their uses.

## We'll cover the following

In TF2, tensors can be of two types: constant or variable. However, TF1 supports placeholders for its default graph execution mode. Here, we explain some properties of both constants and variables.

## TF constants

We can create immutable tensors with `tf.constant()`

, where `tf`

is an alias for TensorFlow. To generate a constant tensor, we can write `tf.constant(15)`

. If we type `tf.constant([6., 4., 3.], [5., 1., 2.])`

, we create a floating-point matrix with two rows and three columns.

We can apply mathematical operations, such as addition, subtraction, multiplication, division, and square, to TF constant tensors. Indexing can also be performed on constant tensors, just like on NumPy arrays.

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